Excerpt: Both this and the identical RMA replacement fit loose and can be heard rattling in the wind when shooting video with my 24-105 Canon lens. neither Canon or B&H have ever heard of this problem and Canon simply suggested wrapping the lens edge with white plumbers tape to sure it up.. I don't think so!
Excerpt: bought this for my 17-40 f/4L and it works perfectly. on a 1.6 crop camera anyway, like my 7d. it blocks a lot more of the stray light than the hood that normally comes with the 17-40. if you are using a full frame camera with the 17-40, then you probably want to stick with the stock hood.