Dynarex Hot Packs provide relief from minor injuries. In 30 seconds or less the Hot Pack will change temperature and provide the affected area with refrigerator-free cold therapy relief. Flexible nylon construction conforms to the contours of the body allowing users to mold the pack to best suit their injury. Packs are free of natural rubber latex. Easy activation of packs offering immediate relief to injured area Flexible material conforms to body contours No refrigeration needed