Enclosed Cabinet AV Cooling fan system with multi-speed control This cooling fan system is designed to be mounted in your enclosed equipment cabinet or computer desk. It will quietly pull the warm air out and exhaust it outside. Plug the power unit into a switched AC outlet on your system, and the fans will only come on when the equipment is turned on or the switch is activated. It has a high-quality, low-noise 120mm fan (with long-lasting and quiet fluid dynamic bearings). It is intended to add serious cooling to your Home Theater, Audio-Visual, or Computer cabinet. In addition, YOU control the fan speed, using the multi-speed fan controller. The 120mm fan is rated at 19 db, while moving 55 cubic feet of air per minute (3/4 speed). The fan has approximately these specs at different speeds: 1/3 speed = 25CFM at 10db, 1/2 speed = 37CFM at 13db, 2/3 speed = 49CFM at 16db, and full speed = 74CFM at 22db (approximate). With cabinet cooling, slow (and quiet) are the way to go! The cooling unit measures 6-1/4" square (includes the mounting plate), and the required hole is approximately 4-7/8" square. The unit is 1-1/4" thick behind the mounting plate, and only requires about 1/3" additional space behind the fans for airflow.