Abstract: A mechanical hand for a robot comprises a pair of change plates each having a slot therein to receive a prong of a finger or gripper. The change plates are slidable laterally of the hand to align the slots with the prongs which may be retained in correct spaced disposition in a pallet. Locking pins are located in aligned bores in plates and have a smaller diameter part which traverses a slot in a respective prong so that when the change plates are moved laterally the larger diameter part of the pins is engaged in apertures in the prongs but will not traverse the slots and thereby the fingers or grippers are retained in the hand. The change plates are movable by means of a piston/cylinder device which may be double acting or single acting with spring return provided.