The mounting tab is an old Rocky Cycle (et al) on-the handlebar mount for these switches. Besides that, the connector on the wires would tell you if it was for a 750K0-K2 (early) or a K2 (late) to K6 type. Or, if it is a CB/CL350 type, being sold by EMGO as CB750, which melts itself apart when used...the key number is not Honda unless it came from their seat-steering-ignition key set ("671" parts kit).