Stem mounts clamp to 10-12 mm round mirror stems for a compact, sturdy and versatile mount. These blind-spot mirrors attached where you need them to keep scan distance minimal. There are two versions available. The short OEM mirror stem version is made for cruiser style mirrors. Here the short mounting space requires the mirror housing to be mounted off to the side while the long stem are made for standard length mirror stems. Aluminum clamps use stainless fasteners and aircraft locking nuts for a quick and secure attachment. Note: A quantity of 1 = a left/right pair. Grade 2 mirrors have either a minor flaw in the mirror that occurred during production or shipment from the manufacturer. Any such flaw will only be perceivable under close inspection and should not be noticeable while riding. Money back guarantee.