Each Joker Machine Mirror requires one of Joker Machine's Bar End Mirror Mounts. Each assembly is UNIVERSAL and works on either left or right side of handlebars - choose the correct mount selection for your application. 1" Bar unit fits: 0.750" to 0.850" - (19 mm TO 21.6 mm) handlebar I.D. 7/8" Bar unit fits: 0.650" to 0.750" - (16.5 mm TO 19 mm) handlebar I.D. Fat Bar unit fits: 0.550" TO 0.650" - (14 mm TO 16.5 mm).