Prior to each usage,the Solar Anti-Mosquito Guard must be switched "OFF" and exposed directly into the sun or artificial light for over 4 hours to fully charge. After completion of a charge, it may last 160 hours to work and can repeat the process. Push the slide switch into position "I, II and III", different Uitra high frequencies are sent out, it can efficiently dispel all kinds of mosquitoes. No hurt for human or animals. If the LED lights when press the button in back of the unit, it shouws energy is OK. Otherwise or weak light, it needs to be charged agiain.