Oregon Scientific Temperature Remote Sensor (OR-THN132N)
A low-cost sensor with an water-resistant casing and a battery cover that's easy to slip on and off. Can be set to one of three different channels. Red LED light notifies when data transmission has been sent. PLEASE CHECK SENSOR COMPATIBILITY WITH YOUR MAIN UNIT BEFORE PURCHASE. Features: Transmits up to 100 feet from the main unit  Temperature Range: -22F to 140F  Resolution: 0.2F  Dimensions: 3.8 L x .9 D x 2.0 H  Requires 1 AA battery.