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.