Instructions: Place one mat face up onto the heating plate of an electric mosquito heater and plug it in. The mat will start working as the indicator light turns on. Replace the mat once it turns from blue to white, which indicates it is exhausted. Always unplug the heater before changing a mat.Ventilation: Keep the room well-ventilated or open windows slightly during use if people or pets are sleeping inside to avoid inhaling dense vapor.Safety: Wash your hands thoroughly with soap and water if you touch the bare chemical mats. Keep the product entirely out of reach of children and domestic animals.