This SAE Aerospace Recommended Practice (ARP) covers the dimensions of an inside splined driver-wrench adapter, envelope of the housing-wrench reaction, the mechanical method of adapting the driver-wrench adapter to the wrench adapter driven end, and the housing-wrench reaction to the holder-counter torque. The purpose of this recommended practice is to provide recommendations for the design of a series of components which, when used as prescribed, will provide a wrench capable of producing up to 500,000 in.-lb of torque.