Product information:Application: double rail seat tube, clamp springColour: BlackSize: Length 25.5cm/Width 16cm, Double track distance 4cmTaillight battery: 3.7V capacity 60mAhMaterial: PVC leather + K8303 bottom shell material, Q235# steel seat beam + polyurethane fillingTail light mode: six light modesTaillight charging time: 1-2 hours fullTail light endurance time: the light is always on for 3 hoursThe duration of fast flashing light is 5 hours, the duration of slow flashing light is 6-7 hoursFeatures: ergonomics, shock absorption, breathability, comfort Packing list:Bicycle seat*1