Single Speed Adjustable Thermostat, Adjusts From 60 To 120 Degrees, To Be Used Only With Roof Mounted & Gable Mounted Attic Ventilators, Can Not Be Used In Conjunction With Whole House Fans, Should Be Used With Model #'s 53828, 53827, 53829, 53830, 53833, 53831, 53832, 53853, 53854, 53315, 53316 & 53319.