Lets the shooter infinitely adjust head placement to get best fit for any type of shooting . . . rifle position shooting, changing between scopes and iron sights, or using a shotgun for both field and trap shooting. Allows comb to adjust four ways: up, down, plus left and right. Comb height is adjusted by sleeves inlet into the cut-off top of the comb, and locked with set screws through side of stock. Left and right adjustment is provided by posts sliding in milled slots in the base plate and locked with set screws. Requires cutting of stock and bedding of plates and sleeves into stock. Stock cannot be returned to original condition. SPL #870 and are individual sleeves attached to separat Mfg: Graco Corp SPECS: Aluminum. SPL #870 - .870" (22.14mm) diameter base.