Universal Round Motorcycle Bar End Mirrors for 7/8" and 1" Handlebars, Cafe Racer Rear View Side Mirror Compatible with Handlebars with M8, M10, M12 Thread Hole (Black). It is also applicable to handlebars with M8x1.25mm / M10x1.5mm / M12x1.75mm screw holes at the tail end.
eBay