The Dogtra ARC HANDSFREE Plus Additional Receiver Remote Dog Training E-Collar with HANDSFREE Square for Discreet and Precise Control Slim Ergonomic Rechargeable 3/4-Mile Range is an expandable receiver that is designed for use with the ARC HANDSFREE Plus. This e-collar comes with a receiver and a compact HANDSFREE SQUARE, which allows you to remotely and discreetly control the transmitter at your fingertips. These ergonomic features are designed to enhance your training, whether for obedience or working K-9 dog training.