DEWALT Impact Torsion Bits TX0 x 50mm (x2) and Magnetic Screwlock Sleeve. The DEWALT 50mm Impact Torsion Magnetic Screwlock Sleeve Sets The impact bits that have a 15 torsion zone that allows the screwdriver bit to flex rather than breaking and the Full Fit head prevents the rounding of the screw head and prevents 'cam out' (bit head slipping out of screw head due to the turning force). The Magnetic Screwlock enables tasks to be completed quicker and easier, reducing instances of dropped or lost screws.