THIS ONLY WORKS ON FREE FLOAT HANDGUARD WITH THE 4 HOLES TO SCREW THE END CAP USING THE SUPPLIED 4 SCREWS. * Will Also Work On Some Yankee Hill Machine Quadrails And Midwest Industries Quadrails (But Non-Threaded front end Types), * Weight: 1oz. Comes with all 4 set screws to install * For .750 barrel. Keeps Debris Out Of Your Rail And Gas Block * Does Not Interfere With Free Floating