Durable USB Rechargeable Battery Built-in 650mAh lithium battery makes these LED bike lights super bright in the dark. Fully charged in 3 hours and lasting over 6 hours, allowing you to avoid unnecessary battery replacement forever. They can be recharged with any device featuring USB ports (PC/ Portable charger/ wall charger/etc) and include over-charge protection. Absolutely the best USB bike lights for cycling enthusiasts Four Light Mode Options -- Both the white front light and red rear light support 4 light modes: Constant Full Brightness / Constant Half Brightness / Blasting Flash / Stroboscopic. By simply clicking the button, you can switch modes as you wish. Light up the road ahead of your bike with a bright headlight and call attention to drivers approaching from behind with the bicycle LED taillight, giving you 360 degree protection. Installed Securely -- Advanced and flexible silicone mounting straps provide great safety, holding the USB-rechargeable bike light set tightly enough to prevent falling off even on bumpy roads. Loosen and fasten them easily without any tools required. Fits all kinds of bikes such as kids bikes/ road bikes. The package includes 2 straps + 2 replacement straps. Waterproof & Light Weight-- Fully enclosed design to protect the cycling light set from rainy days, even the USB port is completely covered, making it convenient to use in all weather conditions. The light weight and sturdy shell guarantees stable performance, which is very important when you ride on complex terrain.