La Crosse Technology TX141TH-B Wireless Outdoor Thermo Hygrometer Transmitting Sensor
Wireless transmitting sensor sends accurate & fast outdoor temperature &humidity measurements with its 433MHz frequency. Place sensor in a dry, shaded location to protect from moisture build-up and direct sun exposure (may cause higher readings.) Good location is on the north side of your house about 18 Inch under the eaves. Weather resistant case and battery powered.
