Manufactured to the highest quality standards the GB750-S™ is designed to fit .750 diameter gas pad barrels and uses a 2 set screw design to securely retain the block in position. Comes complete with, #10-32 X .125” set screws and gas tube roll pin. Places the gas port hole at the correct .295” position from the shoulder.  SPECIFICATION:4140 Gun Barrel Steel.Black Phosphate Finish, Type M.Laser Engraved.Ultra Low Profile.Dia: 0.750” ID.Length: 0.875”.Weight: 1.2oz. Made in the USA