Features: Internal lithium battery, only need about 2 hours to be fully charged while be used for about 12 hours. Super waterproof, make you riding freely regardless of rain. High brightness and energy saving LED. O-ring strap suitable most bike cube (12-32mm). 4 modes: Long bright/Slow flashing/Shun flashing/Strobe. Great for student, baby stroller, jogging, walking, bicycles, car emergency, horse-riding, road emergency & camping, etc. LED Quantity: 5pcs. Brightness: 15 lumens. Casing color for choosing: red . Light Color: as picture shows. Mounting Placement: bicycle seat post. Suitable Tube Diameter: 12-32mm. Running time: Long bright: 4 Hours. Slow flash: 10 Hours. Shun flash: 12 Hours. Strobe: 8 Hours. The charging time of about 2 hours. Size:7.4cm/2.91inch x 3cm/1.18inch x 2.3cm/0.91inch. Package Included: 1 x LED Bike Tail Light 1 x USB Charging Cable NO Retail Box. Packed Safely in Bubble Bag.