This is the 3" mirror size. You need this adapter needed to fit in a bar end of a 7/8" bar
There are two primary benefits of the retracting bar end mirror—added clearance during tight riding conditions, and reduced width for bike storage. The detent folding mechanism is calibrated to retract should the mirror contact an immovable object, thus allowing forward motion without disruption of steering control. The pivot of the hinge features a ball / spring detent which holds the mirror bezel in the full open or retracted positions. The pivot also features dust rings that provide for years of maintenance free operation.
1290 Super Duke R 2020+