Okamoto USA Beyond BodiHeat Pain Relieving Back Heat Pad. Size 3-3/4" x 5-6/5" Non-Medicated Up to 12-Hour Relief Designed to be worn over clothing. Easy-on, easy-off adhesive backing keeps the heat where you need it most. Exclusive formula works with your own circulation to spread the warmth. Pads are air-activated, odorless and nonmedicated.