ADD UNLIMITED PETS TO YOUR SYSTEM: Keep as many pets as you need safely in your yard with this add-a-dog receiver collar. Compatible with all PetSafe In-Ground Systems except YardMax and UltraSmart. RECHARGEABLE: Quickly charges in 2-3 hours with each charge lasting up to 2 months depending on use WATERPROOF: For all of your pet's outdoor activities ADJUSTABLE: with 4 levels of correction plus tone only; fits dogs 5 pounds and up with neck sizes from 6 to 26 inches LOW BATTERY INDICATOR: Let's you know when it is time to charge your collar