A great stock project. Simple installation requires 7/8" and 5/8" spur point or forstner style bits. Makes comb fully adjustable; side to side and up and down. Includes bases, sleeves, set screws, allen wrenches, comb patterns and instructions.Notes: Adjustable side to side, up and downBottom brass base is 1/4" thick, 7/8" wide and 3.390" longUsed with stocks with a low comb