Product Description The easy-to-see face has enlarged scale and raised numbers - -plus it click at every 2?F change Mercury Free Classic Styling Premier Whit Separate temperature setting and thermometer The T87K heat only works with 2 or 3 wire he From the Manufacturer Honeywell heat / cool thermostat. Mercury free 24 Volt, 4 wire Classic styling No batteries required 40F - 90F temperature range Heat / Cool Thermostat. HONEYWEL ROUND HEAT/COOL THERMOSTAT. USE WITH 50010944-001 RANGE STOP. Home Repair, Repair Parts, Fix Plumbing.