SIZE: 1/4 inch hex shank fits for all quick change drill chucks. 4 pieces of 1/4 inch drives, 2 pieces of 3/8 inch drives, 2 pieces of 1/2 inch drives. Perfect size makes it compatible with all brands of power drills and screwdriver handle tools. HIGH QUALITY: Each socket adapter is constructed of heat treated vanadium steel and black oxide coated, and with stand torque compressionwhich is accordance with the standard operating conditions. GREAT DESIGNSpring loaded ball bearings on each square head securely and locks into sockets to avoid slippage during using. DURABILITY: The exterior anti weathering coating provides extra protection from to avoid damage. For example, elements and substances such as include of oil and fluids, that may come in contact with the extension bars during using with repairs, such as in the automotive field. WIDE APPLICATION: The socket adapter is ideal for using on automotive repairs; DIY and most of general household repairs. Size:8pcs Material :Chrome Vanadium Steel Drive system:External Hex, Square Number Of Pieces:8 Color:Black Package include:8*Drill Socket Adapter