The Troy Drop-In Rail is a non free-floating direct replacement for all M4/AR15 Carbine length plastic hand guards with a round end plate. The Troy patented clamping design ensures a solid mounting platform and provides a true optical mounting platform that increases the modularity and accuracy of the M4. Features: a No gunsmithing required. a Installs in minutes a Includes MIL-STD Picatinny rails at 12, 3, 6, and 9 o'clock and four built-in sockets for Q.D. swivels.