Our Locking Extensions offer the most control and are more secure in tight applications. These extensions feature the largest knurling surface on both the shaft and female drive end allowing precision control when hand-tightening fasteners or working with oily materials. In addition to keeping the socket secure with a durable knurled locking collar, these extensions feature a detent hole to increase engagement with the ratchet head for better overall retention. The chrome plating on the extensions offers corrosion and rust protection. All Milwaukee® Mechanics Hand Tools are backed by a lifetime guarantee.