This is a 16-piece set of low profile impact hex drivers with a 3/8" drive system. The set includes both SAE and metric sizes and is made of chrome molybdenum steel with a black phosphate finish. The hex drivers are designed to work with a compatible fastener range of 0.375 inches. The set comes in a package with dimensions of 8.31 x 4.41 x 1.38 inches and weighs 1.96 pounds. The hex drivers do not require batteries and are made in China.