La Crosse Technology TX59UN-1-IT Wireless Thermo-Hygro Sensor for Professional WS-2800 Weather Series

Weather resistant thermometer and hygrometer swiss sensor transmits fast within seconds to your indoor display (compatible only with the Professional Weather WS-2800 Series) from a 200-feet range. Battery powered and measures temperature down to -40-degree F.This sensor only works with firmware 332 & 333. If it is any other firmware, this sensor will not work as a replacement. The Firmware number can be found by initially putting the batteries in your display and the number will flash for a couple seconds in the lower left corner of the display