Deflecto Reusable Microwave Flaxseed Heating Pack for Lower Back provides pain relief for sore muscles and stiff joints, alleviated by moist heat therapy which stimulates blood circulation and increases flexibility. An easy fastening belt design ensures secure heat and pain relief to target the lower back, a long lasting warmth also provides deep muscle relaxation. The fabric should be clean and dry, do not heat if wet. To heat up, lay the flaxseed pad flat in the centre of the microwave for two to three minutes. Shake before use and test the temperature by placing the product to your wrist or inner arm prior to applying to the body.