REPLACED BY MODEL RS4220 The 9400 Series takes comfort to a new level. Our LCD display is up to 80% larger than competitive models. Plus, the display is back lit, making it even easier to read in a dark room. The 9400 Series is loaded with features you will appreciate. Our 9400 model comes with a front load battery door, for no-hassle access to batteries. All models offer permanent winter and summer setpoint memory, allowing you to save both heating and cooling temperature settings. This eliminates temperature adjustments when switching systems for seasonal requirements. And our fully adjustable differential control provides increased comfort for the end user. 2 Heat / 2 Cool with Back Lit Display . Compatible with all standard 24 VAC heat pump systems . Permanent Winter and Summer Setpoint Memory . O & B Terminals . Automatic Compressor Short Cycle Protection . Worry-Free Memory Storage