The Perimeter Technologies Computer ReceiverTM Collar is designed to replace your Invisible Fence brand R21TM collar or add a new pet to your existing Invisible Fence system for a fraction of the cost. The Perimeter Computer ReceiverTM Collar will work with your existing Invisible Fence brand 7K or 10K dog fence system. The collar receiver is completely waterproof and available in 2 frequencies, 7K or 10K (check your current transmitter to determine which frequency you need). Only Perimeter Technologies collars come with patented rubber Comfort Contacts – designed for your dog\’s added comfort and safety. The receiver weighs only 1.1 ounces, making it one of the lightest dog fence receivers available. The Perimeter Computer ReceiverTM Collar is proudly made in the USA by Perimeter Technologies. This ad is for the 7k Invisible Fence® is a trademark of Invisible Fence, Inc. Perimeter Technologies is not affiliated with Invisible Fence, Inc.