A quiet fan kit designed for standard 19 racks, to be mounted on the roof or to replace existing fans. Features a speed controller utilizing PWM which can control the fan's speed without generating noise. Compatible with CLOUDPLATE series rack fans and can be linked to share the same programming. Heavy-Duty steel construction with spiral fan guards, mounting hardware, and power adapter. Size: Standard 120mm Rack Fans Fans: 2 Airflow 200 CFM Noise: 26 dBA Bearings: Dual Ball