Troy One Piece Battlerails TROY TRX (Troy Receiver Extension) One Piece BattleRails are a One-Piece Free Floating Rail, designed for secure installation. Troy TRX rails are custom manufactured from aircraft aluminum and finished in MIL-SPEC Type III hard coat. The lightest, strongest, sleekest,free-floating rail available. FOR: AR15 / M16 / M4- For use with factory barrel mounted sight (carbine). Includes: One 4” & two 2” quick-attach rails and Troy barrel nut Features: - Rotary locking system - Proprietary patent pending one-piece design - Continuous, uninterrupted top rail - Reduced heat transfer - Significant weight reduction - True U.S. Military Specification M1913 rails - Increases target acquisition speed - Free floating design that enhances accuracy - TRX Extreme also includes one 4” and two 2” quick-attach rails for accessories - Includes Troy barrel nut - Flat Dark Earth