The Voltarol Heat Patch is a non-medicated patch which provides targeted back and muscle pain relief by delivering up to 8 hours long-lasting deep penetrating heat. The continuous low-level heat from the patch works by stimulating heat receptors to relieve pain; increasing blood flow to relax stiff muscles, reducing muscle spasms and delivering the body's natural pain relievers. Effective back and muscle pain relief without a tablet, Up to 8 hours of pain relieving heat, Continues to work after the removal of the patch, Thin, self-adhesive and odourless.