Large heavy duty cross section makes it easier on the hands to work on your AR lower receiver. You can remove/install M4 castle nuts with ease with this AR wrench. The castle nut wrench slips over the castle nut and nearly encompasses the castle nut for a more secure fit when installing or removing the M4 castle nut. Makes for assembling/installing collapsible stock buffer tubes a super easy task. The other end of the wrench is for installing/removing A2 Rifle buffer tubes (3/4'')''.