Vltor Carbine Modstock Combo Kit - Starting with a basic chassis/mounting platform, this Modstock allows nearly unlimited mounting possibilities, allowing the operator to adapt to combat environment or mission situations. The unique "Clubfoot" design allows the shooter to hold and support the base of the stock with their non-firing hand. This odd shaped design has proven to provide better control with and a more consistent hold with light machine guns and precision marksmen's rifles. The kit includes a 5-position, mil-spec receiver extension, buffer, spring, receiver extension lock plate and lock plate castle nut.