Double-walled Glass Thermometer for pets is mercury based and accurate to 0.2 degrees Fahrenheit. Reads rectally in one minute and skin surface, groin or auxiliary in two minutes. Double-walled glass, shoulders prevent over-penetration. Measures 4"L and comes with case. Ideal for small animals. Probe Covers are a safe and sanitary way to protect against cross-infection and are sold separately. Label may be different than shown.