The only tool for installing the barrel nut on the aero enhanced upper receiver - Aero Precision M4E1 Barrel Nut Wrench

It does exactly what it is supposed to do. I'm not sure what some of the other reviewers are trying to do with it. The teeth fit into the Aero Enhanced barrel nut (not the Aero Precision B.A.R., which uses a standard free-float wrench). It has a 1/2" square socket for installing on a 1/2" drive torque wrench. If you don't know that this is what it is for or how to use it, please do some research about how to build an AR before you order one.

Note that this is included with all Aero Precision Enhanced Upper Receivers, so you don't need to order this separately!