Therall Body Warmer Patches provide heat therapy to relieve aches and pains from arthritis, joint stiffness, lower back pain, tight muscles, minor strains, tension/stress, and cramps. Air-activated patches provide up to 12 hours of warmth. Patch size is 4" x 5" with a self-adhesive back for use on multiple areas. Safe and easy to use. Use with Therall Joint Warmer Supports (sold separately). Packaged four patches per unit.