yup. i had a bad experience with third party hoods. i ordered one online from CS...and to my horror...it is a little bit smaller than the original one. i've used the 17-55 before so i know wad it looks like. and when i tried fitting it on a 17-40L (not mine)...it wldnt even fit into the threads. so i gave up and sent it back. i made a $4.40 loss. the person didnt even bother refunding my postage when i sent back to him. oh well. i just left it as it is, but i know i'll never buy from him again. btw im very sure its not the wrong model. VERY sure.