Nitecore Rechargeable Headlamp Headlamp with built-in rechargeable lithium-ion battery (Li-ion) can provide maximum operating time up to 47 hours. The NU05V2 can be adapted to the strap or the back of the helmet for warning cars and people to improve safety during nighttime hours. It is equipped with 4 special functions and White lighting. When the NU05V2 is in standby mode, hold down the central power switch for 1 second and the power indicator light will flash to indicate the remaining battery power. Three flashes indicate that the battery power is above 50%. Two flashes indicate that the battery power is below 50%. One flash indicates that the battery power is below 10%. It is rated IP66, making it functional in all weather conditions.