The KT Pro 3/8" Drive Impact Sockets, Nos. A3403MP, A3405MP, A3404SP and A3406SP, are available in SAE and metric sizes. SAE sizes range from 1/4” to 3/4” (A3403MP and A3405MP), and metric sizes range from 7mm to 19mm. All KT Pro impact sockets are made with quality chrome molybedenum alloy steel and are precision heat-treated for maximum torque strength. These sets are backed with a lifetime warranty.