This part of ISO 11900 specifies the dimensions and tolerances, in millimetres, of ball-lock punch retainers, type A (rectangular) and type B (square), for light duty, and of their backing plates. The main use of ball-lock punch retainers and their backing plates is the retention of ball-lock punches, in accordance with ISO 10071-1, when punching holes in steel sheets. It gives material guidelines and hardness requirements, and specifies the designation of ball-lock punch retainers in accordance with this part of ISO 11900.