Precision Reflex Barrel Nut Wrench for AR15 Assembly Tool Black. The wrench is designed for a 20 hole pattern barrel nut on a Radius of .78in. Specifications for Precision Reflex Barrel Nut Wrench: Manufacturer: Precision Reflex Fabric/Material: Steel Color: Black Condition: New Finish: Nitrite Gun Model: AR-15 Features of Precision Reflex Barrel Nut Wrench for AR15 Assembly Tool: Constructed of 3/8" steel with 5 steel tightening pins can use a 3/8 or a 1/2 driven torque wrench The wrench is designed for a 20 hole pattern barrel nut on a Radius of .78" Package Contents: Precision Reflex Barrel Nut Wrench What firearm models does the manufacturer say Precision Reflex Barrel Nut Wrench is compatible with? The manufacturer suggests that Precision Reflex Barrel Nut Wrench is compatible with AR-15Precision Reflex 05-0082: Barrel Nut Wrench for AR15 Assembly Tool Black