Milwaukee Shockwave Impact Duty Insert Socket Adapters are engineered for extreme durability and long life. Made from proprietary steel and heat treated to control hardness. Designed for use with Milwaukee Shockwave Magnetic bit tip holders. Heavy duty construction for fastening capabilities in all impacts. Set includes: (1) Insert 3/8" Socket Adapter, (1) Insert 1/4" Socket Adapter and (1) Insert 1/2" Socket Adapter.