Petsafe Free To Roam Extra Wireless Collar. This extra receiver collar can be used to add another dog or as a replacement collar to the Free to Roam Wireless Fence, Stay+Play Wireless Fence, or the Wireless Pet Containment System. The Free to Roam receiver collar includes 5 levels of static correction plus tone only, adjustable to your pet's temperament. Features Ergonomic collar design provides added comfort for pets Operates with RFA-67D-11 battery module; expected battery life is between 1-2 months For dogs 5 pounds and up Fits neck sizes 6-28 inches Tone-only mode alerts your pet with a beep Waterproof and submersible Low-battery indicator Compatible with Free to Roam Wireless Fence, PetSafe Wireless Pet Containment System (PIF-300 system, IF-100 transmitter) and Stay+Play Wireless Fence (PIF00-12917)