Daniel Defense's Rock & Lock Fixed Rear Sight is easy to install and is highly versatile. Its one-piece design pairs perfectly with Mil-Spec flattop upper receivers, and secures itself via slotted fasteners which are threaded into a self-locking steel thread insert. The Rock & Lock Fixed Rear Sight is machined from 6061 aircraft grade aluminum and features a hard coat anodized finish for durability and a long service life.