Specification: Brand Sofirn Input voltage 2.8-4.2 V Electricity Direct-stick Diameter 16.8mm 2 groups: Group 1: Low 5% PWM Mid 30% PWM High 86% PWM, double click strobe 86% PWM. Group 2: moonlight Low 5% PWM Mid 30% PWM High 86% PWM SOS 86% PWM, double click strobe 86% PWMLow voltage protection: Yes. The light is automatically extinguished when the voltage is lower than 2.8 volts. The signal is that the light is slowly flashing for 1 minute Group Set Operation: When on, 3 click continuously, the light 2 times & then automatically go to next mode group. Package included:1 x 2 Groups circuit board driver