NcStar Pro Series AR Lower Receiver Wrench Features Pro Series AR15 Lower Receiver Wrench heavy duty purpose built M4 castle nut wrench for collapsible stock buffer tubes 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 . 1/2 and 3/8 drive compatible, for torquing your barrel nuts to the proper torque specifications. All the tools are Clearly Labeled. Hole at the end is for hang Specifications Material Steel Construction Length 12 1/2 Weight 18 oz Color Black SOLD QUANTITY 1