If you are talking about a video camera I use one from
www.helmetcamera.com on my motocross helmet and also when I do trackdays on my streetbike. Its aluminum case is contoured to the contours of a helmet, comes with a rechargable battery pack. All you have to do is plug it into a small handheld video camera thats in a fanny pack of backpack. The video camera still records the footage, this is a lens that attaches so it's hands free.
http://www.wristtwisters.com/forum/a...8&d=1165812503