So I recently acquired a CANON EF 200mm f/2.8 ll USM and started looking at mounting rings. To my surprise, there only seems to be two in existence from Canon for this lens and the only difference is the color and price, roughly $40 difference. Canon Part #: 2889A002, "Canon Tripod Mount Ring A" WHITE Canon Part #: 2888A002, "Tripod Mounting Ring A for 200mm f/2.8L II" BLACK I personally could care less about color, but when looking for information on the cheaper one, it seems that it is extremely hard to find or maybe discontinued. I see tons of the 70-200mm version on ebay (Tripod Mount Ring A (B) for Canon EF 70-200/300mm Lens), but wanted to know if those are even compatible with my lens. I'm new to the ring mount world and didn't have a need for one till now. Thanks for any help.