The Dogtra 4500 EDGE e-collar is designed for dog owners and trainers that need advanced features such as customizability, expandability, and durability. The 4500 EDGE handheld transmitter is a tube shape that fits right in your hand, which makes one-handed operation easy with an interchangeable stimulation dial that offers a smooth and precise Rheostat Dial or an immediate and intuitive Selector Dial with clicks. The 1600-metre 4500 EDGE is expandable up to a 4-dog system.