Helps with getting low profile optic mounts to a more comfortable cheek rest height and shooting position; Mounts via a Locking Quick Release mount onto the Picatinny rail of your AR15/M4 receiver; There is a see through channel below the rail to keep the mount lighter and for some firearm types, it may allow you to use some factory iron sights; Black anodized aluminum construction; Length: 5.3 in.; Weight: 4.2 oz.