This insert contains 1.5 lbs. of natural lava sand. It can be warmed in the microwave for up to 90 sec. Place a cup of water in the microwave with the item. Enjoy the soothing warmth for up to 2 hours, and reheat when the product is at room temperature. To use as an ice pack, place in the Lava Ice Bag and place in the freezer for 2-3 hours. This will help ease bruises and sprains and also reduce temperature.