California Code, Penal Code - PEN § 16680

As used in this part, “hard wooden knuckles” means any device or instrument made wholly or partially of wood or paper products that is not metal knuckles, that is worn for purposes of offense or defense in or on the hand, and that either protects the wearer's hand while striking a blow, or increases the force of impact from the blow or injury to the individual receiving the blow. The composite materials, wood, or paper products contained in the device may help support the hand or fist, provide a shield to protect it, or consist of projections or studs that would contact the individual receiving a blow.