Features:

Thermostat Works Standalone or with the Thm5421R1021 Equipment Interface Module or with the Truezone Wireless Adapter
Patented Interview Based Programming and Installer Setup
Redlink Wireless Communication
Plain Language Setup, No Manual Needed
Extend Wireless Range of the Equipment Interface Module by Connecting a Wireless Adapter to the ABCD Terminals
Dual Powered Battery or Hardwired
Precise Temperature Control
Energy Star Rated

Specifications:

Manufacturer: Honeywell
Manufacturer Part Number: TH8321R1001
Product Type: Programmable Thermostat
Color: Arctic White
Voltage Rating: 18 to 30 VAC/750 mV @ 50/60 Hz
Display Size: 10 sq. in.
Power Method: Battery/Hardwired
Terminal Type: Screw
Switch Positions: Heat-Off-Cool-Auto (System), Auto-On-Circ (Fan)
Terminal Designation: R, RC, C, W (O/B), W2 (AUX/E), Y, Y2, G, A-L/A, K, U1, S1, Changeover Auto/Manual
Ambient Temperature: 32 to 120 Degrees F
Setting Temperature Rating: 40 to 90 Degrees F (Heat), 50 to 99 Degrees F (Cool)
Dimensions: 6.45" x 5.3" x 2.3"
Weight: 1.01 lb.