The so-called Wrench Tool serves to fix the Delta Ring (which is the part which fixes the handguard in the M4 or M16) and the Stock Tube. The tool is made of metal and is also suitable for situations where a lot of pressure has to be exerted. It should be kept in any case measure and not tightened too tight because both the Delta Ring and the Stock Tube could otherwise be damaged. Especially with Systema PTW or other rifles wired to the rear, care must be taken that sharp edges on the tube can sever the cables and cause a short circuit.
