Model SP155 is a thermostat for the heat traced cable outdoor Models 8317CTFP and 8317CTFP.220V. It has hermetically sealed contacts. Guards against overheating and cold spots. Opens at 62 °F (17 °C) and close at 52 °F (11 °C). Shuts off heat at 55 °F. Class 1, Division 2, Group B, C, D explosion-proof.