【Reasonable Structure】Dimensional composition of the stepped installation wrench: 3/8, 1/2, 3/4, 1-1/4 inch, 21mm square drive. 【Durable Chrome Vanadium Steel】This ratchet wrench is made of strong and durable chrome vanadium steel with the best dimensional accuracy and high hardness value. 【Driver】The stepped wrench of this radiator is designed with a 1/2" (12.5mm) internal square driver. Since the 1/2" ratchet wrench directly drives the square driver, no adapter is required. The bolt wrench can be placed directly on the 1/2" ratchet wrench. 【Wide Applications】This ratchet wrench is suitable for sanitary ware and radiators, faucets, workshop equipment, automotive parts, assembly and disassembly of radiator valves, return fittings, faucet extensions, thermostats, drain fittings.