AiPhone IS-HTR HEATER MODULE TO MEET TEMP. RATING OF -40º F / -40º C (IS-DV/DVF, IS-IPDV/DVF, IS-DVF-2RA/HID/HID-I, IS-SS, IS-SS-CI/RA/RA-R/2RA/2RA-R/HID/HID-I), Part# IS-HTR