ISO/TS 21108:2005 specifies the dimensions and tolerances for the interface between impulse wrenches and their power sockets: output spindle of power tool/female drive end of power socket. This interface is based on the principle of a socket centred on the cylindrical spindle. Alternative dimensions and tolerances for two options, A and B, are provided. It is applicable to both pneumatically and electrically driven impulse tools, and could also be used in other applications.