Bests & Worsts Reviews from Amazon

These work very well for walking the dog (or cat) for an hour or so. Done two or three times per day, have the hand warmers in my coat pockets. No need to shake them, in my pockets they stay until I return home. When they're not being used, place them in a zip-lock sandwich bag, roll out the air and zip it closed until you need it again. Keep a mental note of how many hours this pair has been used so you'll know when to open the next pair. Doing it this way, I've gotten 6 days out of one pair with no loss of heat with each rejuvenation!