Summary: I purchased the hood and used it on my 15-85mm lens. It mounts easily, on the bayonet part of the lens, so no problem if you want to use/change filters and can be reversed for storage. Very practical. It is also covered with non-reflecting material (inside part) to avoid reflections from light. Don't waste your money and time on some cheap product that is not going to work.
Summary: I recently purchased the Canon Tli and the 15-85mm IS USM. I had hoped to purchase the corresponding lens hood at the same time but, alas, it was not immediately available. I checked Amazon as well as several other sellers with no luck. Turned out one of the Amazon merchants, Adorama, showed they had some available so I ordered from them. Turns out their claim of available stock was incorrect and I later received a back order notice from them.
Summary: Having purchased a cheaper alternative, I experienced severe vignetting but only in one corner. I finally bit the bullet and purchased the Canon version and the problem was solved. Side by side the two hoods were similar but the third party one was thicker and taller.
Pros: Durable, Fit For Purpose, Rugged, Strong Construction
Excerpt: I am a keen photographer and as such I have a lot of equipment that helps me to produce a much better end product. Canon has always been my manufacturer for choice, simply because I think it's the best all round performer (although Nikon comes in very close behind). I have the Canon EW-78E Lens Hood to fit onto my EF-S 15-85mm f/3.5-5.6 IS USM lens - and was actually thrown in free when I bought this zoom lens a few years ago.
Pros: Attaches to barrel . Non - reflecting coating . Sturdy . Canon .