"24V DC Cooling Fan" There Certification: When consumers buy electric fans, to see the instructions to see if the mandatory certification quality system certification, whether there is inspection standards certification; and now promote "green carbon", but also see whether the level of energy efficiency standards. Noise: The main component is the motor fans to make noise in the selection of fan noise must listen whether the motor running, look at it in operation whether jitter is stable; good motor let you in a quiet environment , only to hear the wind, "whispers", ultra-quiet fan blowing air is good. "24V DC Cooling Fan" no odor: odor is the smell of varnish coating on the fan copper produced during operation, in the purchase of fans have to smell it, to see this paint is environmentally friendly, whether through quality testing, so that you enjoy the fresh air in the cool wind. "24V DC Cooling Fan" Electrical Safety: Safety requirements for electric fans, the national standards set forth in a very detailed, consumers can be a simple test. Qualified fan, general adult fingers can not touch the fan grille and front, families with young children should choose dense fan grille.