The design of this Yankee Hill Specter Gas Block will allow the user to mount forearms that will extend beyond the standard gas return system, provided the inside diameter of the forearm is 1-5/8 inches or greater. It allows the mounting of the forearms without the removal of your pinned or welded muzzle accessory. This Specter Gas Block consists of a simple, durable, two-piece design that is mounted by the use of four socket head cap screws using a 7/64 inch Allen wrench. It is made from high quality steel and finished with a Mil. Spec. phosphate coating. This Gas Block will last for years to come.