It is made of aluminum alloy CNC-machined,Smooth surface, Rust-proof and durable.Fits for Handlebars diameter :19mm-33mm or 19mm-40mm, with single screw model you can Install only one bottle cage.With double screw model you can Install one bottle cage in middle or two bottle cage on both side, but you can& 39;t Install three at once with double model.Item Name: Bottle Conversion SeatMaterial: Aluminum AlloyModel: 1: Single Screw, 2: Double ScrewScope Of Application: General Purpose For Bicycles, Electric Vehicles And MotorcyclesGeneral Installation: Seat Tube / Swallow Handle / Straight HandleFeatures: Lightweight, Portable, DurableSingle Screw Conversion Seat Size: 7.7cm x 4.6cm/3.03" x 1.81" (Approx.)Double Screw Conversion Seat Size: 7.7cm x 5.3cm/3.03" x 2.09" (Approx.)Single Screw Conversion Seat Installation Pipe Diameter: 19mm-33mm/0.75"-1.3" (Approx.)Double Screw Conversion Seat Installation Pipe Diameter: 19mm-40mm/0.75"-1.57" (Approx.)Notes:Due to the light and screen setting difference, the item& 39;s color may be slightly different from the pictures.Please allow slight dimension difference due to different manual measurement.Package Includes:1:1 x Single-Screw Conversion Seat (Bottle Holder Not Included)1 x 2.5mm Inner Hexagon1 x 3.0Mm Inner Hexagon1 x Thick Protective Gasket1 x Thin Protective Gasket2:1 x Double-Screw Conversion Seat (Bottle Holder Not Included)1 x 3.0mm Hexagon Socket1 x Thick Protective Gasket1 x Thin Protective Gasket