The T 5 dog device with collar is a top-mounted, high-sensitivity GPS/GLONASS receiver that uses LED beacon lights activated from the Astro 320 and Alpha 100. The lights work in low light conditions and at night, and are visible for up to 100 yards away. Rugged and water resistant to 10 meters, this tracking-only dog device is tough enough to run wherever your dog runs, up to 9 miles away. T 5 units, when sold separately, ship with a 1-inch blue collar strap. By Garmin.