Slap bracelet

A slap bracelet (or snap bracelet) is a bracelet consisting of layered, flexible stainless steel bistable spring bands sealed within a fabric, silicone, or plastic cover. The bracelet can be straightened out, making tension within the springy metal bands. The straightened bracelet is then slapped against the wearer's forearm, causing the bands to spring back into a curve that wraps around the wrist, securing the bracelet to the wearer.