The Femto USB Drive Rear is a compact and lightweight USB-rechargeable LED cycling taillight. Its durable co-molded construction is minimal and has an IPX7 waterproof rating. A versatile mounting strap quickly mounts to a variety of post sizes. Five output modes offer up to 5-lumens and the custom Wide Angle Optics lens provides up to 270Adeg of visibility. The Femto USB Rear can run for up to 15 hours and is easily rechargeable with the included Micro USB cable. A secure, threaded Composite Matrix cover keeps the USB port clean and sealed. The Femto USB is perfect for commuters and recreational riders looking for a simple and inexpensive way to add visibility. SPECS: Max Lumens: 5 Max Runtime: 15 hours Battery Capacity (mAh): 210 Recharge Type: Micro USB Weight: 24g Dimensions: 41.8mm, 43.8mm, 31mm Features: IPX7