Seller Warranty - We offer 24 Months Manufacturer's Warranty. Please feel free to contact us if you encounter any quality issues.No Standalone lithium batteries are sold with the product.USB C Rechargeable Bike Lights , Quick charging via Type-C, fully charging within 1.5 hours. And the light can be up to 50 hours of battery life. quick press the power button to show remaining battery capacity. Press and hold the power switch for 5 seconds to turn on/off the brake sensor function. IPX6 waterproof, suitable under all weather conditions.Group ride flash mode in this new version, which only emits 10 lumens and provides 50 hours of long runtime. In addition to this, we also redefine the smart mode. Now you can use the maximum output of 200 lumens during the daytime, which greatly improves the safety of daytime riding.Smart Bike Taillight with Smart Brake Sensor and Ambient Light Sensor - With the brake sensor active, the bike light automatically detects a lane change or a sudden stop and increases brightness to 200 lumens for 3 second. NOTE: Runtime will be reduced significantly with brake sensor active.Multiple Mounting Options - Default mounts include a length adjustable silicone strap compatible with seat-posts of various sizes, a seat rail mount that hooks onto the two metallic rails under the seat, and 2x zipties for any DIY or helmet setup.