Small Uniheat Pet Shipping Warmer (Adhesive). Simply remove heat pack from sealed packaging, peel the sheet off the adhesive side, and stick to the side of the box. We've been using Uni Heat heat packs to ship aquatic plants for years with much success. Feel free to reach out for advice about optimal use. **Please note, the heat packs expired 8/12/2024. However, we find these remain just as effective well past the expiration date. -Designed for reliable and steady heat release for 40+ hours. -Simple to use and deliver optimal results with color indicator on the warmer. -Excellent for shipping live insects, reptiles, tropical fish, flowers, aquatic plants, etc. -Provides an average warmer surface temperature of 100 degrees F (38 degrees C) -Optional adhesive back so one can stick the heat pack to the wall of a package or other surface.