SPECS: Dimensions: 2" x 3.7" Weight: 0.1lbs Materials: iron, vermiculite, salt, other natural materials 98% biodegradable; contents inside warmer sack can be composted after use DESIGN & DETAILS: Air-activated design Perfect to keep in your car, use for emergencies, or keep you comfortable on cold-weather excursions Enjoy up to 10 hours of heat from each warmer (2 inside each pack) to stay toasty on your chilly adventures For fast heat, remove the warmer, shake it, and enjoy industry-leading heat output in about 5 minutes For prolonged all-day heat, remove the warmer, shake it, and put it back in its pouch Heat from natural minerals and oxygen is safe and comfortable Compact and portable design Resealable and reusable temperature regulation envelope allows you to save one hand warmer for the next day