Same here lots of different transmitters. Temperature stations, wireless anemometer, VP2's. The Mfg. Code on transmitter makes it clear for me if the offset is needed.
If you ignore the letters, different products have own unique letters and they change but all transmitters work the same and have a date. Any date January 2016 (1601) and going forward are the new transmitters.
Example here AK1307 was made in 2013, month 07 so needs the -.9 offset if using the new SHT31 sensors.