Sun Company ZipperSnapper - Micro Zipper/Keyring Thermometer | Mini Outdoor Zipperpull Thermometer THE SMALLEST PERSONAL THERMOMETER - At only 1.3 inches long and 0.2 oz in weight, ZipperSnapper is the smallest, lightest-weight personal thermometer on the market. CUSHION MOUNTED THERMOMETER - Reads down to a chilly -20 degrees Fahrenheit HANDY KEYRING - Attach to your coat, pack, or anything else you can think of.