A REPLACEMENT SENDING UNIT OR OIL PRESSURE SWITCH BOOT. THIS ISFOR SWITCH THAT SCREW INTO YOUR TIMING COVER.THEBOOT FITS ALL TRIUMPH 500, 650 AND 750MODELS 70 AND UP.PLEASE NOTE THAT IF YOU BELIEVE YOURSWITCH HAS FAILED YOU SHOULD STILL TEST OIL PRESURE FROM YOUR PUMP THAT HAS THIS PARTICULAR SWITCH.