Rackmount fan panel sized for a half rack measures just 1.75" x 10.40" x 1.63". Each of the four fans has a 1.57" diameter. A thermostat probe automatically activates fans when the ambient temperature reaches 86 degrees F [30 degrees C] and deactivates them when the temperature reaches 72 degrees F [22.2 degrees C]. This power saving feature ensures efficient fan operation while saving wear and tear on the unit.