Keenso -- Bike Seat Post Bottle Rack Converter Bike Saddle Back Double Water Bottle Holder Adapter Features Light weight, high strength, no deformation, corrosion resistance, clear appearance.Using high-quality aluminum alloy, high hardness, oxidation resistance, wear proof and durability.Install the water bottle adapter for riding with two water bottles on the road. The special design is convenient to pick up the bottles.Strict quality control, high safety factor, can be used with peace of mind.High cost performance aluminum alloy material, solid and firm, convenient installation, can be installed two bottle rack durable. How to Use Step 1: Place the gasket on the two pipes of the cushion. Step 2: Align the screw hole of the bottle adapter with the screw hole of the washer. Step 3: Insert the hex screw and tighten the screw with a hex wrench. Step 4: Easy installation is complete. Specification Item Type Double Water Bottle Holder Adapter Material Aluminum Alloy Weight Approx.146g/5.1oz Package List 1 Pcs Double Water Bottle Holder Adapter; 6 Pcs Screw; 2 Pcs Gasket; 1 Pcs Aluminum Alloy Sheet