The new PetSafe Stay + Play Wireless Dog Fence Receiver Collar can be used to add more dogs to your present fence system or to replace a worn out collar. It is totally compatible with the PetSafe PIF00-12917 Sit + Play Fence and the PetSafe PIF-300 Instant Fence transmitters. The collar is specially designed for dogs weighing more than 5 pounds with neck sizes from 6 to 23 inches. The collar is entirely waterproof and has a rechargeable battery that can be totally recharged in 2 to3 hours. Any number of dogs can be contained so long as each dog is wearing a Stay + Play receiver collar around their neck. Just like the original collar that comes with your wireless dog fence system, this extra receiver collar features 6 levels of correction including a tone-only feature for training.