To put it simply, Airtouch 3 has been discontinued. Airtouch 3 is excatly the same as Airtouch 2, but doesnt allow the use of the ITC sensors. Airtouch 3 was replaced by Airtouch 4 in 2019 and if you require individual in room temperature sensors, this is the way to go. If you want to use ITC sensors, simply opt for Airtouch 4. If you would like Airtouch 3, look at the information for Airtouch 2.

Airtouch 2 has all the functions of Airtouch 3, looks and feels the same.
Find out more information here at Master Aircon.