SEEMEE 30 tail light mounts to the back of the seat post using the included rubber strap. The 30 lumen LED is has 3 brightness modes. The light come complete with an enclosed 330mAh polymer battery and is recharged with common USB charge ports using the included mini USB cable. 
 
Features:
3 brightness modes with up to 30 lumen max output
270 degree, 800 metter visibility
2 (at full bright) to 40 hours of operation on a single charge
Light sensing
IPX 6 Waterproof
65mm x 15mm x 21mm