Pneumatic clamping fasteners are designed for quick change applications. Instant pneumatic clamping reduces setup time in multiple-parts holding and frequent changeover of machinery or fixture. These pull down fasteners are designed to be used with QCPC-series clamping pins. The piston on these double-acting fasteners goes up by air supply from clamping port and the balls move toward the center to pull down the clamping pin. Fasteners unclamp when air is supplied from unclamping port. The inner spring on these double-acting fasteners can provide clamping force without air supply. The body is made from 304 stainless steel. Wedge and balls are made from 440C stainless steel, quenched and tempered. The piston is made from 303 stainless steel.