Multi-Dog Expansion Collar: The SportDOG TEK Series 1.5/2.0 GPS Tracking System Add-A-Dog Collar allows you to add and accurately track an additional dog on your TEK Series GPS Tracking System Durable & Waterproof: Rugged, submersible collar and handheld device built for outdoor use with long-lasting rechargeable batteries and low battery alerts Compact & Expandable System: Lightweight smart setup with adjustable scale and multiple correction modes for flexible and customizable remote training Built for the Field: SportDOG gear was designed by professionals who demand durable, no-nonsense tools that perform in real-world conditions without fail Trusted by Serious Trainers: Professionals rely on SportDOG for proven performance, consistent control, and expert-backed training guidance that gets results US version only 10-mile range DRYTEK waterproof and submersible to 25 feet Compatable with TEK 2.0 systems only