I ordered and just received the AquaTech SS200. The quality of the cover is very good but...there is no way to access the lens. This cover may be good if you are using a prime with autofocus, but it is extremely difficult to use with a zoom or to manually focus. I'd also like to mention that AquaTech's website lists the SS200 for use with the 100-400L but the cover only fits the lens when it is retracted to the 100 position. I tried the cover over my 24-105 which Aqua Tech also says this cover fits. It does fit but you cannot zoom the lens. THe elastic band that helps keep the cover snug covers most of the zoom ring on the lens making it rather difficult to use.