[Isolates the interior from the outside air] - This air curtain is not an air conditioner, and will not generate cool and hot air. Do not buy this unit if you need an air conditioner. The air curtain is a powerful fan that forces a high-speed airflow over the inlet to isolate the indoor and outdoor air environment while blocking out 90% of hot or cold air, dust and smoke. [Free Optional Door Switch] - With the door switch installed, the air curtain will automatically turn on when the door is opened; turn off when the door is closed. The door switch is optional, if you do not install the door switch, press the ON/OFF/HIGH speed switch to operate for 8 hours continuously. 9、WARNINGS a)、Use the unit with the rated voltage and frequency indicated on the nameplate. b)、Disconnect the power supply before servicing the unit. c)、Routine maintenance should be performed every year. d)、Never use gasoline, benzene, thinner or any other chemical to clean the unit. e)、Do not allow water or any liquid to enter the motor. )、When the power supply comes from a socket, the plug must comply with IEC335-1. When the power cord is connected directly to the power supply, ensure that a suitable circuit breaker is installed to comply with local standards and regulations.