4 Modes bike rear light: features 4 lighting modes with a single switch, including full brightness, half brightness, fast flashing, and slow flashing, providing high visibility from a distance and enhancing safety during nighttime riding USB rechargeable design: equipped with a built-in 330 mAh rechargeable lithium battery and USB charging port; compatible with any USB-powered device for convenient charging; includes a USB cable for charging via computer, power bank, or other USB-enabled devices Easy to install: silicone mounting strap with 4 openings allows quick and secure attachment to handlebars, seat posts, and other compatible locations; fits most standard sizes without the need for additional tools Wide compatibility: suitable for various bicycles including road bikes and mountain bikes; can be mounted on bike frames, seat posts, handlebars, or helmets; also ideal for use on belts, running gear, reflective vests, backpacks, dog collars, and harnesses Bright and reliable: 5 LED design delivers 15 lumens of brightness; red light color enhances visibility in low-light conditions Mounting position: seat post Bulb type: LED Suitable pipe diameter: 12-32mm Operation: long press to turn on/off Color: red Material: ABS+PC Size: 7 x 2 x 1.7 cm Package includes: 2 x lights, 2 x straps, 2 x USB cables Note: the taillight may arrive with a partial charge; fully charge before first use. For best results, ensure proper charging. Product content: only items listed are included; others not included Note: lighting and display differences may cause slight color variation between the image and actual item. Measurement may vary by +/- 1-3 cm