Keep your hands warm this season with this cute reusable hand warmer. Available in 2 assorted designs: Cat, Dog. To heat pocket warmer, snap metal circle until the liquid solidifes and becomes warm. To reuse add the hardened hand warmer into boiling water and let sit for approximately 5-10 minutes until the crystals have dissolved. Once the heat pack has cooled down - reuse it at any time. Sodium Acetate Liquid, PVC, Metal.