The PetSafe Pawz Away Extra Receiver Collar allows you to add another pet to your Pawz Away Indoor Pet Barrier (sold separately). Lightweight and waterproof collar sports Progressive Static Correction technology to help your pet avoid problem areas. Adjustable strap for excellent fit. For pets up to 5 lbs. or with neck sizes between 6 and 28. Also works with the PetSafe UltraSmart In-Ground Fence system (sold separately). Requires two 3-volt lithium batteries (included). Manufacturers limited one-year warranty. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Electronic Collars.