Opinions Please

[am_pitbull_terrier]

Has anyone ever used this product? If so what do you think about it? I would like to get something like this so feel free to make any suggestions.
http://www.bhphotovideo.com/bnh/controller/home?A=details&kw=LUSBM&is=REG&Q=&O=productlist&sku=93262

Thanks

[OdiN1701]

http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=32690&is=REG&addedTroughType=search

Get that one. It won't block the AF assist beam from your 580.

[am_pitbull_terrier]

Thanks, I didnt see that one.... Have you ever used it? If so what did you think about it?