Handwarmer packs can be used, but you must remember that your typical handwarmer, alone, can take anywhere from 45-60 minutes to heat a cold bottle of sample to 100 degrees. Thats why you should preheat your sample first, then activate the handwarmer.

Youve mentioned going through the Dunkin Donuts drive-thru, and the 45 min drive.... Don't overlook your vehicles heater as a source for preheating the sample. :thumbsup: