These Two-Speed Pet Crate Fans provide a refreshing airflow for pets wherever they travel, or while at home. Fans circulate the air, removing warm air from the cage interior, and can help to protect pet from overheating. Their quiet, two-speed operation will not disturb pets. The standard Crate Fan features a built-in thermometer to measure ambient temperature, and a port to accommodate an AC/DC adapter (not included). The standard Crate Fan comes in Silver. An optional Cooling Cartridge features a freezer pack insert and snaps onto the front of either model fan to add extra cooling power for up to two hours. Additional replacement freezer pack Refills are also available and sold separately. A 6-Volt AC Adapter allows the fan to be plugged into an electrical outlet. Comes with a 6' cord. 12-Volt DC Car Adapter plugs into car's cigarette lighter outlet to run fan while traveling. Comes with a 20' cord.