IRWIN 3555531C Screw with Retracting Sleeve, 1/4 in Hex Drive, 1/4 in Hex Shank, Steel                Engineered to hold long fasteners in place, the screw guide sleeve retracts as the fastener is driven into the workpiece. For use with insert bits only. Magnetic for better fastener retention, reduces fastener from slipping and wobble. Hex shank of size 1/4 in.