UniHeat 72 Hour heat packs were designed to be safely used with live insects, reptiles, animals, plants, and other sensitive things. They can be used for shipping products anywhere from 1-3 days. We use this heat pack the most because it provides a steady temperature averaging 100°F (38°C). They are very simple to use and full instructions are on the back. Just open the package and expose the heat pack to air to activate. Preheating before usage is not necessary. You can add the heat pack directly to your shipments fresh out of the package and they will heat up within 30 to 45 minutes if kept in an enclosed air space (like wrapped in paper or placed inside a paper bag). We recommend these in most of our winter shipments.

All of our Heat Packs are FRESH! We do not sell Near Out of Date Heat Packs! If a Heat Pack is out of date, they will not properly warm up or stay warm.