The Ko-ken RS4129/5-L37 1/2" Square Drive Bolt Twister Set is an essential tool for recovering broken bolts with missing heads, offering a reliable solution for difficult fastener removal. This set includes five bolt twisters in sizes 8mm, 10mm, 12mm, 14mm, and 16mm, each designed to grip the broken bolt securely. To use, simply drill a hole in the center of the broken bolt, insert the bolt twister, and turn it left until it grips the bolt, allowing for easy extraction. Each bolt twister has a length of 37mm and is conveniently organized on a 150mm rail for easy access and storage.