DAIKIN AIR HUB | LINEAR CONTROL KIT | UPTO 4 ZONES DAIKIN Airhub Touch Zone Box 4 Zone Linear 24V Our Linear Control solution enables you not only to turn on or off but also set the zone temperature to within ±2°C from the main set point. Daikin’s Linear Control also features our proprietary OptiZone Control. 4 Zone, Linear Zone Controller Box (24V)