Analog + Digital Mercury-Free Min/Max Thermometer – Sper Scientific Direct
Max-Min Thermometer - Hummert International
Digi-Sense Liquid-In-Glass Maximum/Minimum Thermometer; -35 to 50C (-30 to 120F), Organic Liquid Fill from Cole-Parmer
Amazon.com : Brannan Digital Max Min Greenhouse Thermometer - Greenhouse Temperature Monitor to Measure Hi and Lo Temperatures in Greenhouse Garden or Home - Easily Wall Mounted Greenhouse Accessories : Patio, Lawn & Garden