I'm looking for a word to describe the type of hand-cuff straps used in, for example Avatar the film. They begin as a straight strip with a curve like a tape-measure, then when you "crack" them they curl around the wrist.
OK, I have no idea about The Avatar, but your description reminded me of product for bicyclists. Apparently it is a reflective band that is called "Slap and Wrap", and you can buy it on Amazon.
As far as I remember, they come as a solid piece, that is "slapped" over ankle or wrist. They are also called "slap bracelets".