The GORILLABOX acoustic box fan is one of the quietest and most compact on the market. It contains a high-quality UK manufactured Torin Sifan squirrel cage fan (unlike many budget box fans that use significantly cheaper/louder Chinese motors) lined with 12mm superior soundproof acoustic foam. The internal Motor is mounted within the Fan and is attached to the casing with lock/ tight anti-vibration nuts. Housing the fan in an 18mm MDF box means it is cheaper than its metal counterpart and the superior construction makes it air tight and quiet running for the amount of air moved. The GORILLABOX acoustic box fan can be CUSTOMISED in many ways from motor sizes to multiple inlets/outlets of many sizes, from straight through design to 90-degree (right angle) inputs/outputs and is able to have adjustable flow rates using the GORILLABOX or other proprietary speed controllers. The GORILLABOX Fans all have glued and screwed MDF panels. The flanges are all pre-mounted with a bead of silicone sealant which is used to create a seal against the MDF to ensure peak permanence with no air leaks.