PetSafe in-Ground Cat Fence for Cats Over 6 lb, Waterproof, Tone and Static Correction, Stretch-Section Collar for Safety Adjustable waterproof receiver collar fits cats with neck sizes from 6 to 11 1/2 Inch Collar includes stretch section for cat's safety; avoid leaving the receiver collar on your cat for more than 12 hours per day Complete system for up to 1/3 acre but may be expanded up to 25 acres with additional wire and flags Receiver collar correction can be adjusted to cat's temperament ( 4 levels plus tone only for training) Low battery indicator reminds you when battery replacement is required Collar uses replaceable RFA-188 battery Call, chat or email with our expert PetSafe US-based customer care specialists six days a week; They are waiting to assist you and your pet with your product needs PetSafe brand has been an industry leading US manufacturer of pet behavior, containment and lifestyle products since 1991, helping millions of people and pets each year