The Hunting Series is a Dual Function tracking light that is waterproof, crushproof, very bright and long lasting. It will operate in flashing mode for over 250 hours on a single battery pack. The batteries are common CR2032 coin cells that are available most anywhere. This unique design was specifically engineered to lock on the industry standard one inch "biothane" type encased nylon collars found on most all radio collars. Comes with 2 battery packs.