Polar Mitten Camera Cases are designed to keep your camera functioning properly in cold weather. They are thickly padded with high-loft insulation material. Air-activated warmers are placed along the case interior to keep battery, recorder, lens and hands warm in extreme cold temperatures (Tested at –50 degrees Fahrenheit).The insulated lens cap protects the lens in transport and also prevents condensation from forming when bringing the camera in from the cold.Each Polar Mitten Case comes with 4 air-activated heat packs. Additional packs (PHP-2) can be ordered directly.