This temperature instrument is special made for the Sauna environment. The face and rim are high heat withstanding plastic for safety reasons. The 4" diameter rim is chrome plated for an appealing finish. The Dial is both in Fahrenheit and Celsius. For optimal Sauna air temperature indication, install away from the Sauna Heater. Dial shows from 32°F to 240°F (0°C - 120°C)