Specifications: 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't Install three at once with double model. Item Name: Bottle Conversion Seat Material: Aluminum Alloy Model: 1: Single Screw, 2: Double Screw Scope Of Application: General Purpose For Bicycles, Electric Vehicles And Motorcycles General Installation: Seat Tube / Swallow Handle / Straight Handle Features: Lightweight, Portable, Durable Single 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'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 Hexagon 1 x 3.0Mm Inner Hexagon 1 x Thick Protective Gasket 1 x Thin Protective Gasket 2: 1 x Double-Screw Conversion Seat (Bottle Holder Not Included) 1 x 3.0mm Hexagon Socket 1 x Thick Protective Gasket 1 x Thin Protective Gasket