I got one of these for my 200L 2.0 that I recently purchased. I was quite worried that 200L did not have a lens cap and I bought this cap thinking It works like a regular lens cap.
My initial impressions with the lens cap was that it wouldn't stay on properly. It comes with these over sized "o-rings" that Don says you should use. There are 3 of them, using 3 of them makes it impossible for the cap to fit. Using 2 of them also does not work. Using 1 of them sort of works, but it requires a lot of force to put it on.
One another problem I had with the lens cap, and it was the main reason why I returned it, is the edges of the handle is extremely sharp. I ended up cutting my fingers after using the cap just for a few minutes.
I paid $60 for the cap and for $60, I was expecting a lot more. At least they could have made the handle part of the cap more user friendly (or should I say finger/hand friendly). Also, because the handle is made of very hard rubber, it doesn't fold and does not fit in your pockets. So the entire point of not using the cap thing that comes with the actual lens and using this cap to me was the ability to carry this cap around easily and I was hoping it would be more practical. I was wrong.
Now I am using what the lens came with and it's really not bad. I don't use that thing if I am going out with only 200L and the body, the hood is large and long enough to protect the front element. If I am going out with multiple lenses, then I use that big pouch thing and it's not a big deal really because when I don't need it, I can keep in my back pack.