1/2 " Sizes: 17 - 22mm Left reverse special hand grips wire Made from chrome molybdenum steel Supplied in a blow molded case Professional tool for occasional or commercial use Twist pullers for removing broken studs, pipes, screws, grease nipples Special left-handed reverse thread sockets touched for strength and durability This precision kit allows you to extract hex screws that are corroded or seized and must be removed without damaging the casing or thread manufactured from chrome-molybdenum steel for maximum durability will be able to easily bite and grip softer bolts This hollow twist is specially designed to remove rounded bolts and bolts studs < / p> As you turn the socket counterclockwise the spiral cutter blades grip and remove the nut or stud 1/2 “drive for s ‘adapt any which 1/2 pawl drive / power bar extensions SET INCLUDES THE FOLLOWING SIZES 17mm / 19mm / 21mm and 22mm comes in a case blow molded for easy storage and transport also comes with a straight bar 12mm