Product Details A quiet dual-fan kit designed to be mounted onto the roof of standard 19-inch racks to provide cooling. Containing standard 120mm fans, it can also replace existing fans that may been included with your rack. Maintaining an optimal temperature for rack-mount equipment prevents overheating, ensures constant performance, and extends their lifespan. Features an inline speed controller utilizing PWM-technology. The fans are housed in heavy-duty cold rolled steel with spiral fan guards. They are CE and RoHS certified, containing dual-ball bearings that are rated at 67,000 hours and allow this fan system to be mounted horizontally or vertically. This complete kit includes two fans, an inline speed controller, rack-roof mounting screws, four rubber washers, corded 6-ft power adapter, and user’s manual. Precise Speed Controller The inline speed controller enables you to set the duct fan’s speed to optimal noise and airflow levels for various environments. Unlike common AC-powered duct fans that suppresses voltage to control fan speeds, this duct fan features a DC-motor that is precisely controlled using PWM (Pulse Width Modulation). This technology enables the fan's motor to be able to run smoothly at extremely low RPM speeds without generating motor noises and heat as seen on variable voltage controllers. Eight speed options are available with power switch, and backup memory. Performance and Applications This rack roof fan kit contains standard 120mm fans, enabling it to be compatible with most standard 19” racks. With a noise level of 26 dBA, the fan system can be used for environments where low or minimal noise is required such as home theater, studio, DJ, and audio video racks. A max airflow rating of 200 CFM will provide sufficient cooling to server, network, IT and equipment racks requiring high airflow.