The Dogtra EDGE e-collar is designed for dog owners and trainers that need advanced features such as customizability, expandability, and durability. The 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 1-mile EDGE is expandable up to a 4-dog system. Download Manual for EDGE IPX9K WATERPROOF RATING: This unit has been tested and has received a waterproof rating of IPX9K. The Ingress Protection (IP) rating classifies the level of protection provided by the exterior casing and electrical enclosures against a variety of elements. Dogtra's IPX9K rating has been specifically tested for waterproof protection. This unit was tested at close range using powerful water jets with high pressure and high temperature over various points.  Learn More about IPX9K