I found this guide to be very thorough... If you are considering buying a cup and are wondering which one? http://menstrualcups.wordpress.com/2008/06/11/my-comparisons-and-ratings/
There is some animosity in the MC world regarding the Moon Cup USA, made by Keeper. It's too close in name to the Mooncup UK and they are both silicone and apparently people have been ordering on eBay what they think is a UK and its a USA. The big differences are that the Moon Cup by Keeper (silicone Keeper- is the nickname I will mostly refer to it as to avoid confusion) is smooth and not vegan friendly. Being smooth makes it easier to clean but harder to remove. The MCUK is matt, vegan and the stem is better. To be honest I was confused... I thought I had the UK and gave the USA to my sister, but it was the opposite way around. Some very observant people may have noticed the “switch-a-roo” recently. However if you and a few friends want a Keeper or a Moon Cup USA pop on over to http://www.keeper.com they have a “3 for the price of 2” deal going, there does not seem to be an expiration date... This deal is not available on their Moon Cup website. I got a little confused till I read the URL, I thought it might have been a hoax.
It's better than a tampon, it worked for me as a “first time” cup and was my prefered cup for night time. A little difficult to remove due to the wide rim. It’s not a cup I would recommend for teenagers, you might hate cups forever if this was your first. For sexually active women over 25 or who have had babies, the ridge might not be such a problem. It never fails to pop open, its always the one fold and the one position. But it holds less liquid, and the rigid rim means it is less “cramp friendly” than its competitors. What I mean by that is for my experience, (and other bloggers have found this too) on a crazy heavy day I will always have some “crampidge” when I was a tampon user, sometimes I would find if I used a pad on a non- ridiculous day the cramps would go, and on a ridiculous day, the tampons would make the cramps worse.
Removal and reinsertion can be difficult while you are learning, so its beneficial to have a cup that allows you to go optimally over 8 hours, as the learning curve can be frustrating, oh but completely worth it so keep trying. Once it is in there is not much difference in the feel of a large cup to a small cup. So why put yourself through that more than you need to?
What I did not realise in the first few months is that removal is a technique too. Breaking the seal and walking it out works but folding it back into a C fold makes it come out “more agreeably, but yes it is a little messier”. This takes practise.
I totally recommend it to ladies who have a heavier flow and a fairly tight schedule though it has a slightly higher learning curve than other models. Some of my friends have a smaller cup that they change 2x/day in the shower. I obviously have a heavier flow, so that did not work for me with the Silicone Keeper, but it works very effectively with the JuJu. While other silicone cups open for me perfectly every time, the JuJu seems to change, one time its the 7 fold with this position and the next time it wants a C fold in that position (on the 3rd go)... since writing the above, I have found the c fold in the squat position to be the most effective on a regular basis.
Getting a (larger) JuJu out when you are a rookie; did a kid at school ever sting you with a rubber-band wasp? Yep... I rest my case. You definitely do not walk this baby out and it is most suited to heavy days which I have found that I am more “open”. Being a smooth silicone, with less defined ridges, its harder to grip when removing than the Moon Cup USA is and it did ruin my manicure. Yes it is still my favourite, after reading what I have written you can be forgiven for wondering why? Maybe it's the pretty purple bag it came in. But mostly its because I can leave it in for longer on a heavy day, going to work and not having to worry about leakage... There is also the feel of quality about the JuJu that is better than the silicone Keeper and MeLuna. The JuJu is seamless and appears to be made of very good quality silicone, and does not stain as much as the silicone keeper.
Ok I have a new favourite cup and it is the Ruby. She arrived today, I was working on my assignments and Honey came in with a pink parcel. To be honest I thought at 3pm that I had missed out again today, but it came with the regular post. I swear its not the pink envelope or the pink ribbon on the bag, or the fact that its named after my favourite gem...
Ruby is comfortable to insert even on a dry run day... I could not resist and I am glad I tried. The Ruby cup is also a dream to remove... the ridges are not quite as pronounced as the MeLuna ones but they give pretty good grip- much better than what I am used to with the JuJu and silicone keeper. The stem is nicer and has better grip, and the quality of the silicone appears to be right up there with the JuJu.
The best of all my cups and combined (quality silicone, good grippers, easy to insert and remove, feels comfy)... with the social justice. We have a winner. I can totally recommend this cup for a first time user or an MC addict. What's more, over half the women in the world who own a Ruby cup used a Ruby Cup for the first time and its the only one they have. The Ruby cup is an Outstanding cup in my grading system, and I would absolutely recommend it for a first time user.
I am not going to lie, its expensive, however not the most expensive cup I own. Two Ruby cups on special in a sister deal was 80 AUD by the time I paid for postage and pay-pal fees... On the flip side, I no longer waste $90+ every year on sanitary products either- so even though I went with quality, I'm still winning. In the end you need to decide what is best for you, your pocket, and your body.