Benefits of moist heat therapy over dry heat are well established for pain relief due to arthritis, myofibrosis, back pain, muscle strains and spasms | Trusted by physiotherapists, physicians, chiropractors, athletic trainers and kinesiologists for over 60 years | Each all-natural HotPac contains bentonite, a natural hydrocolloid filling, and is wrapped in a woven cotton blend | Delivers up to 30 minutes of deep, soothing relief and can be reheated as needed | A cost effective treatment, each HotPac can be used hundreds of times, and is engineered specially to prevent the growth of mildew