This is a solid, hardened steel wrench for those barrel nuts, has a 1/2 in. drive hole that I used to put a 1/2 power bar on, You should also have a proper housing unit to securely hold the AR receiver that is shown here also both unit package is $100.00 OBO please be aware that shipping can get costly with Canada Post This barrel wrench is specifically designed for Sig ARs if you are working on a Sig you need both. the barrel wrench cost me $100.00