The 15" Trinity Force M-LOK Free Float Rail features ultra slim profile with front and rear picatinny attachments. Also included are 4 polymer picatinny rail attachments with steel hardware. An all steel barrel nut is included along side shims for correct fitment. Designed to be used with mid-length, rifle length or Mil-Spec M16 rifle length gas systems. For your safety, Trinity Force recommends this part be installed by a competent, qualified gunsmith/installer with an understanding of the weapon platform that the part is being installed on. Always make sure the firearm is unloaded and pointed in a safe direction when working.