Rub A535 Dual Action Back Patch - Hot to Cold Rub A535 Dual Action Back Patch is a soft, cooling patch that activates to provide penetrating heat for temporary pain relief exactly where you need it. The flexible patch is not messy or greasy, adheres comfortably and removes easily. The warm soothing relief lasts for up to 4 hours. Starts out COLD to ease the pain .... Then turns HOT for soothing relief. Large Size for Lower Back 4 patches 10cm X 21cm (4" x 8 1/4")