Air Arms Monte Carlo walnut stock Fits S400, S410, S500 & S510 air rifles Right-hand Ventilated rubber buttpad Checkered pistol grip and forearm Raised cheekpiece * If you bought your Air Arms precharged pneumatic gun with a beech stock, you can upgrade it to this walnut beauty. Did you break or ding your walnut stock? This is the replacement that'll make it right, again.