GearWrench 80664 1/2-Inch drive hex bit socket, 19 millimeter bit size. Heat treated steel socket for durability and serviceability. Hex head style has internal dimple feature which forces bit surface to the opposite side of socket wall for maximum fastener retention. Hex bit has black oxide finish for non slip capability. socket has high polish nickel chrome finish for long tool life. Sizes are hard stamped on sockets for easy identification.