Leapers Spring-Loaded Low Profile Flip-Up Rear Sight for AR15 is constructed of aluminum with a black finish and a low profile. Spring-loaded posi-lock push button activation automatically deploys sight tower and prevents sight tower from collapsing when deployed. Features tool-free windage adjustment and dual apertures ideal for a variety of different scenarios. Utilizes a single locking Torx screw 3mm locking bolt and mounting deck. Torx Locking plate Recommended Torque Value: 35 in-lbs.