What is the Physio Room.com Reusable Hot / Cold Gel Pack (large)? A versatile 25cm x 17cm (10" x 7") mouldable gel pack that can be used as either a cold pack or hot pack. When can I use it? This great value product is useful at all stages during the recovery from injury, & can be used again & again. Use it as an ice pack during the early stages following injury to help minimise pain, bleeding & swelling in the tissues. Use it as a heat pack later to help the healing process by increasing local blood flow & promote relaxation. Size The hot/cold pack measures Approx. 25cm x 17cm (10" x 7"). How does it work? The soft gel in the pack conducts heat or cold. Simply cool in a refrigerator or freezer & it will stay cold, or warm in hot water (or microwave oven) in order to use it as a hot pack. Always follow the manufacturers instructions.