From inside (document excerpt):
Honeywell Thermostat Selection Guide. Compare thermostats models: VisionPRO™ 8000 Touchscreen Programmable, FocusPRO™ 6000 Programmable, FocusPRO 5000 Non-Programmable, PRO 4000 Programmable, PRO 3000 Non-Programmable and The Digital Round™. Free User’s Manual Guide in PDF format.
Models included:
TH8110U1003
TH8320U1008
TH8321U1006 with dehumidification
TH6110D1005
TH6110D1021
TH6220D1002
TH6220D1028
TH5110D1006
TH5110D1022
TH5220D1003
TH5220D1029
TH4110D1007
TH4210D1005
TH3110D1008
TH3210D1004
T8775A1009
T8775C1005
Source: honeywell.com