CTC 43658 Remote Indoor Temperature Sensor. For use with CTC thermostat models 43058 and 43558 Wire with 2 conductor thermostat wire Measurement range 15 - 99 degrees F Accuracy +/- 1 degree F Maximum connection distance - 328 ft. with 20 gauge 2-conductor wire 3-1/4" X 2-1/2" H X 5/8"