SpotSee Digi-Temp® 7 and 16 Level Thermometers are based on proprietary formulations of liquid crystals that change color at a designated temperature. The Digi-Temp thermometers offer a -22°F to 248°F (-30°C to 120°C) Temperature range with an instant response and continuous readout. The SpotSee self-adhesive thermometers provide a non-toxic solution, requiring no batteries or glass.