Mirror head is designed to slide up or down on stem to achieve the best viewing position Bright chromed housing and stem True-vision, no-distortion nonglare flat glass mirrors accurately indicate distance of things to the rear Extra-long 9" stems for 6" up/down adjustments. Housing secures to stem with a set screw and hex wrench included. Vibration-stop nut locks mirror in place. For cycles with 10mm screw-in mirror mounts. Housing is 5-1/8"W x 3-5/8"H. Stem is 3/8" diameter. Dimensions are approximate. Sold in pairs.