3" Stroke Gooseneck Chipping Hammer. Uses round shank chipper steel. W-Style Threaded. When conventional tapered style retainer chippers fail prematurely, the acme thread style chipping hammers are put into service. The heavy?duty retainer mechanism has two sets of steel sleeves and a rubber bumper to disperse and absorb the blows of the chisel. W?style chippers use oval or round collar chisels.