We've got you covered, whether you're organizing a cold weather event or making sure your employees are warm in cold conditions. Each pair lasts 8 hours and provides fast heat that doesn't need to be recharged or reheated. They're safe to use, convenient to pack in a backpack or toolbox and can be disposed of with regular trash. Grabber® Warmers are made with natural ingredients that don't harm the environment and have a 4 year shelf life if stored in a cool, dry place.