As a stem height extender for handlebar to ensure comfortable riding; Made of aluminum alloy, well-structured, solid and durable; Wide compatibility to fit carbon, alloy and steel forks; Concealed mount design combines practicality and aesthetic appeal; Available in one size (55mm) to meet personal preference; Lightweight, quick and easy to install; Fork riser outer diameter: 28.5mm, inner diameter: 23.3mm; Fits carbon fiber, aluminum alloy or steel steerer tubes; Screw hole: M5, compatible with standard stem M5 bolts (bolt not included); Installation requires M6 hex key (tool not included); Color: black + silver; Material: aluminum alloy; Dimensions: 160 x 23mm; Package includes: 1 x bike stem extender; Note: Light reflection and different displays may cause slight color variation between image and actual item. Measurement allows an error of +/- 1-3cm.