Steel, dual function wrench lets you easily remove your old extension tube and install a new-style, A4 stock. Spanner has three lugs to fit the A4-style castle nut. Provides a non-slip fit so you can correctly torque the stock to the receiver. Also, the comfortable, rubber coated handle features a cutout to fit the receiver extension tube to remove the A1 or A2 stock. SPECS: Steel, parkerized finish. 7-5/8" (19.3cm) long.