"Includes the following: 4MM, 5MM, 6MM, 7MM, 8MM, 9MM and 10MM (3/8"" Drive) and 12MM, 14MM and 17MM (1/2"" Drive). Chrome socket base heat treated for durability and serviceability. Patented bit holding principle features internal dimple which forces bit surface to the opposite side for maximum retention. S2 and alloy steel bits. Includes slide rail"