AR-15 EASY JIG by 80% Arms UNIVERSAL 80% . The universal fit Easy Jig™ is a patented device that makes machining your 80% lower easier, faster, and safer. Lowers finished with the Easy Jig™ have a better finish and hold tolerances that could not be achieved using any other jig on the market today. You do not need to own a drill press or mill to use the Easy Jig™. It truly makes finishing your lower a monkey simple process. On top of all this, it’s extremely durable and can be reused for dozens of lowers.