Our AR15/M4 Dual Function Spanner wrench tool is made of Steel for strength & durability. It comes with a rubber coated handle that provides a comfort grip & non-slip easy torque handle. It is used to assist in easily removing your old extension tube and installing a newer style A4 Stock. It also features a cutout to fit the receiver extension tube to remove the A1 or A2 stock. A Great tool for any Rifle Enthusiast or Gunsmith.