IRIS USA adhesive hand warmers reach temperatures up to 142°F and provide up to 12 hours of warmth. These large warmers feature an adhesive backing that sticks to clothing, making them ideal for placing on underarms, shoulders, back, or chest for whole-body warmth. The simple activation requires just opening the package and shaking; they heat up fully in 15 to 30 minutes. Made with natural ingredients including iron powder, vermiculite, and activated charcoal, they are odorless, non-toxic, and TSA-approved for travel. Each warmer measures 4.8 by 3.7 inches.