Nuts also know as an "chocks" and are "passive devices" devices (see Cams). A mechanical device, first used in Wales and then brought to the US by Royal Robbins. Nuts are inserted into a crack in the rock and substitutes for a piton as a way of attaching a rope to the cliff face. This is call "protection" and climbers use it to protect against a fall. They can also be used for direct aid.