FLEX ® Menstrual Cup (Originally the Keela Cup) – Full Review

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Note: We're just reviewers of the Flex Cup, we don't sell it. However, you can get the best deals by shopping on the list above.

Flex Cup Sizes and Models

The Flex Cup is a menstrual cup that is manufactured in USA. It is made of Silicon and comes in 2 different sizes/models:

Note: Similar cup design/model can be found under the following name(s): Keela Cup
Flex Cup
Slim Fit
43 mm
74 mm
46 mm
28 mm
20 ml
25 ml
3 /5
3.5 /5
3.5 /5
Flex Cup
Full Fit
46 mm
82 mm
54 mm
28 mm
30 ml
35 ml
2.5 /5
3 /5
3 /5
Found any errors in our measurements? Let us know!

Introduction

The Flex Fits Company has taken possession of two alternative menstrual products to date.  

The SoftCup by Instead is now the Flex Disc. This is a menstrual disc that collects the menstrual flow but is shaped like a diaphragm. It is also folded and positioned differently than menstrual cups. These discs were designed specifically to be worn during sexual intercourse while on your period and are disposable.

The second menstrual product that the Flex Fits Company took over is the Keela Cup. The Keela Cup first campaigned on Kickstarter and is reusable. This cup was designed with a unique “pull-string” for easy removal but ran into some manufacturing trouble. Flex Fits stepped in and now the cup has been rebranded into the Flex Cup and ReleaseRing™.

An 8 discs, two month supply of The Flex Disc starts at $12.99. They also offer a subscription type purchase through their website if you choose. The Flex Cup, on the other hand, can be purchased online or in some big chain stores across the USA for $40, at regular price.

This review is for the Flex Cup and not the Flex Disc.

YouTube Videos

Model 1: Flex Slim Fit | Review

What’s Included

When purchasing the Flex Slim Fit Menstrual Cup, you will receive the smaller, narrower, and shorter cup of the two sizes that they offer. An instruction manual and pouch are included and the well-packaged box may or may not come with two Flex Discs to sample.

Who is it Meant For?

According to the Flex site, the Slim Fit Cup is “best for beginners, for period pros, and for people who are tired of outdated menstrual care”. Which at first glance leaves the guesswork up to you.

However, there is a circled question mark after the ‘Choose Size’ title that gives a more detailed guide. The guide here reads that the Slim Fit Cup is also meant for users with a light to medium flow, has the capacity of two super tampons (22 ml), and for first-time cup users. They recommend this size if you are unsure which size is right for you.

As these cups are on the shorter side, I would suggest getting an approximate measurement of your cervix. Although the ReleaseRing™ allows you to customize the stem slightly, if you have a high cervix, this cup might still be a challenge to reach.

Special Features

Capacity – While the Flex Site states that the cup holds 22 ml, the ReleaseRing™ design may compromise the result during use.

Body – This cup is bell-shaped with a rounded base and a standard secondary and upper rim. Although bell-shaped cups are favored by users with a low cervix, this cup has a hard area at the base in which the stem passes through. It may pose comfort issues depending on where the user’s cervix is located.

Stem – The original design of the Keela Cup was all about the “pull-string” stem. It was said to make removal “as easy as changing a tampon”. This unique design features a stem that is attached to the inside of the upper rim and then threaded through the base of the cup. When the user is ready to remove the cup, they pull on the loop at the bottom which draws the upper rim into the cup and releases any suction.

Because the stem can be extended slightly, it is adjustable by about a 1/4 inch. However, if extended too much, it will collapse the rim.  

The stem can be pulled (out) easily but hard to push back in. The cup will likely need to be removed if an adjustment needs to be made. Since the whole stem is needed to work as intended, it can not be trimmed.

Rim – Although the rim is a thicker, rounded band of silicone at the mouth of the cup, it is still about the same firmness as the rest of the body. Whereas most menstrual cup rims are at least slightly firmer. This may cause difficulties when trying to get it to open. Again, the stem is attached to the upper rim.

Secondary Rim – The secondary rim almost reaches the halfway point in the middle of the cup. The silicone here is a little thicker than the rest of the body, but not as thick as the upper rim. It smooths the transition between the body and rim but is still about the same firmness. The secondary rim on most menstrual cups is at least slightly firmer than the rest of the body of the cup.  This softer secondary rim may cause difficulties when trying to get it to open.  

Grip Rings – The Flex Cup does not have any grip rings on the base or stem.

Silicone Quality – Although there are several cups made with this particular silicone, it still isn’t as popular as the liquid silicone rubber (LSR) that we normally see. This silicone seems much more like a High Consistency Rubber (HCR), similar to cookware & bakeware.

HCR can be medical-grade. The difference between food-grade and medical-grade silicone is a matter of biocompatibility testing (both in LSR and HCR products). This test ensures that the silicone does not pose any toxic threat to living tissues. HCR silicone needs a post-curing process and must be cured correctly to eliminate all volatiles. 

Since I have not contacted the Keela or Flex Fits Companies directly, I can’t say with 100% certainty that the Flex Cup is made with this process.  I can only compare it to other HCR products.

Firmness – The base of the Flex Cup is on the firm side due to the hole in the center where the stem is threaded. This hole is built up with extra silicone to make it sturdy enough that blood will not leak. However, the rest of the cup – the body and rim, are on the softer side. When squeezing the cup, you can feel the solid, thick, stem in the center of the body.

Air Holes – There are four medium-sized holes located on the secondary rim about 3 mm from the upper rim and are equidistant. These holes should be easy to clean since they travel in a straight path to the inside of the cup.  

Seams – Because of the unique design, this cup has flash lines or seams that can be found in unusual places. There is one on the outer side of the rim, one around the inside of the rim, and one that travels the length of the stem, around the loop, and back up to the other side. The inside of the loop has flash lines, as well. While none of these should cause any irritation during use, it may take some extra care while cleaning. 

Markings – The Flex Cup is only available in an opaque black which makes any marking hard to see. However, they still branded the inside of the cup with their name FlexCup and measurements 3.5 & 5 ml.

Colors: black.

Model 2: Flex Full Fit | Review

What’s Included

When purchasing the Flex Full Fit Menstrual Cup, you will receive the larger, wider, and longer cup of the two sizes that they offer. An instruction manual and pouch are included and the well-packaged box may or may not come with two Flex Discs to sample.

Who is it Meant For?

According to the Flex site, the Full Fit Cup is “best for beginners, for period pros, and for people who are tired of outdated menstrual care”. Which at first glance leaves the guesswork up to you.

However, there is a circled question mark after the ‘Choose Size’ title that gives a more detailed guide. The guide here reads that the Full Fit Cup is also meant for users with a heavier flow and has the capacity of three super tampons (30 ml). They recommend the Slim Fit size (small) if you are not sure which size is right.

If you have a medium to a high cervix, I would suggest choosing the Full Fit Cup as it will have the length that will make it easier to reach during removal. Users with a medium to a low cervix will probably be more comfortable with the Slim Fit Cup as it is shorter.

Special Features

Capacity – While the Flex Site states that the cup holds 30 ml, the ReleaseRing™ design may compromise the result during use.

Body – This cup is bell-shaped with a rounded base and a standard secondary and upper rim. Although bell-shaped cups are favored by users with a low cervix, the Full Fit Cup should be long enough to give users with a high cervix the length that they need. 

It should be noted that the base of this cup has a hard area in which the stem passes through. It may pose comfort issues depending on where the user’s cervix is located.

Stem – The original design of the Keela Cup was all about the “pull-string” stem. It was said to make removal as “easy as changing a tampon”. This unique design features a stem that is attached to the inside of the upper rim and then threaded through the base of the cup. When the user is ready to remove the cup, they pull on the loop at the bottom which draws the upper rim into the cup and releases any suction.

Because the stem can be extended slightly, it is adjustable by about a 1/4 inch. However, if extended too much, it will collapse the rim.  

The stem can be pulled (out) easily but hard to push back in. The cup will likely need to be removed if an adjustment needs to be made. Since the whole stem is needed to work as intended, it can not be trimmed.

Rim – Although the rim is a thicker, rounded band of silicone at the mouth of the cup, it is still about the same firmness as the rest of the body. Whereas most menstrual cup rims are at least slightly firmer. This may cause difficulties when trying to get it to open. Again, the stem is attached to the upper rim.

Secondary Rim – The secondary rim almost reaches the half waypoint in the middle of the cup. The silicone here is a little thicker than the rest of the body, but not as thick as the upper rim. It smooths the transition between the body and rim but is still about the same firmness. The secondary rim on most menstrual cups is at least slightly firmer than the rest of the body of the cup. This softer secondary rim may cause difficulties when trying to get it to open.  

Grip Rings – The Flex Cup does not have any grip rings on the base or stem.

Silicone Quality – Although there are several cups made with this particular silicone, it still isn’t as popular as the liquid silicone rubber (LSR) that we normally see. This silicone seems much more like a High Consistency Rubber (HCR), similar to cookware & bakeware.

HCR can be medical-grade. The difference between food-grade and medical-grade silicone is a matter of biocompatibility testing (both in LSR and HCR products). This test ensures that the silicone does not pose any toxic threat to living tissues. HCR silicone needs a post-curing process and must be cured correctly to eliminate all volatiles. 

Since I have not contacted the Keela or Flex Fits Companies directly, I can’t say with 100% certainty that the Flex Cup is made with this process. I can only compare it to other HCR products.

Firmness – The base of the Flex Cup is on the firm side due to the hole in the center where the stem is threaded. This hole is built up with extra silicone to make it sturdy enough that blood will not leak. However, the rest of the cup – the body and rim, are on the softer side. When squeezing the cup, you can feel the solid, thick, stem in the center of the body.

Air Holes – There are four medium-sized holes located on the secondary rim about 3 mm from the upper rim and are equidistant. These holes should be easy to clean since they travel in a straight path to the inside of the cup.  

Seams – Because of the unique design, this cup has flash lines or seams that can be found in unusual places. There is one on the outer side of the rim, one around the inside of the rim, and one that travels the length of the stem, around the loop, and back up to the other side. The inside of the loop has flash lines, as well. While none of these should cause any irritation during use, it may take some extra care while cleaning. 

Markings – The Flex Cup is only available in an opaque black which makes any marking hard to see. However, they still branded the inside of the cup with their name FlexCup and measurements 7.5 & 15 ml.

Colors – black.

Flex Menstrual Disc vs Flex Menstrual Cup

The Flex Disc is a ‘one-size’ item that resembles a diaphragm more than a cup. It has a large, firm ring with a thin, flimsy reservoir to collect menstruation. The Disc is folded in half and inserted back towards the tailbone and tucked above the pubic bone. The thin and flimsy reservoir allows for penetration while on your period. The Flex Disc is supposed to be a one-time use item to be thrown out after each use. However, many users have been known to assume the risk and wash and reuse a single disc for the duration of their period. Although it is not advised.

The Flex Cup is a reusable, bell-shaped cup that is folded into a smaller insertion point and inserted directly under or around the cervix to collect menstrual fluid. It is not meant to be worn during penetrative intercourse.

Detailed User Manual

The Flex Fits website has a short video about the cup’s design, how to choose a size, and how to use the cup in five steps. It also has brief descriptions, animated gifs, and a few FAQs if you rather read.

Customer Service 

Alternatives to Flex Cup

While there is no other cup on the market that has a ReleaseRing™, there are some cups that can offer the same shape, size, or firmness depending on your needs.

Venus Cup – The Venus Cups are of similar body length as well as firmness to the Flex Cups in both sizes. However, the large Venus Cup holds a substantial amount more (47 ml) than the Flex Full Fit Cup (30 ml). If you’re looking for a cup with a higher capacity, the Venus Cup might be a better option.

Saalt Cup – If you have a medium to a low cervix and are looking for something slightly shorter without a hard base, the Saalt Cup may be a more comfortable option. These cups are available in two firmness levels and have a rounded body like the Flex Cups. 

Summary

The reviews have been split between users who love the design and the ease of the Flex Cup’s ReleaseRing™ and those who found it harder to use than a traditional menstrual cup.  

The concept and design are inventive, but I don’t feel like it was executed in a way that will work for many users like myself.  

First, the pull tab (loop) was very stretchy and felt like it was going to break, although it never did. It made it difficult to know when the actual stem was going to start moving.

Second, the part of the stem that is attached at the rim was in the way of allowing my cervix to rest as it normally would. In my case, within the cup. This kept the cup positioned low enough that I could feel the hard stem pass-thru when I walked or sat a certain way. It also prevented the cup from making a seal as it needed and caused the cup to leak.  

Third, when using the stem as intended, it collapsed the rim against my cervix causing pain and irritation and I felt that it created a suction when it was pulled when it was supposed to aid in releasing it.

The original design was supposed to make using a menstrual cup easier. However, I feel like the unique stem makes it a little trickier to fold and harder to place correctly. It may be difficult for users who don’t have good hand strength or movement to thread the stem into the cup and down through the hole at the base. And lastly, cleaning everything will require a little more attention as there are extra areas that are not normally found on other cups.

Frequently Asked Questions

Can you poop with a flex Cup in?

Many users can “pee & poo” as normal while their cup is inserted. However, if you don’t feel comfortable doing so, you can remove the cup beforehand and re-insert it after.

Does Flex Cup leak?

Correctly placing the Flex Cup and emptying it on a schedule can help eliminate leaking.

Is flex a menstrual cup?

Flex Fits offers two types of alternative menstrual products. The Flex Disc is shaped like a diaphragm, while the Flex Cup is reminiscent of the more traditional bell-shaped menstrual cups on the market.

How do you insert the flex menstrual cup?

The Flex Cup is folded into a smaller point, then inserted back towards the tailbone. Make sure the cup has opened completely by inserting a finger to check for pleats or indentations.

How long can you wear a flex cup?

Like most menstrual cups, the Flex Cup is safe to wear for up to 12 hours depending on how light or heavy the menstrual flow is.

Can you rinse and reuse Flex?

The Flex Cup is reusable and should be rinsed and reused as needed.

How do I know if my Flex is inserted correctly?

If the Flex Cup is inserted correctly, you should not feel any pleats or indentations, nor should you feel the cup at all.

6 Total Score

Overall Score
6
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