A top-mounted, high-sensitivity GPS/GLONASS receiver, TT 15 dog device uses 18 levels of continuous and momentary stimulation, plus audible tone and vibration activated from Alpha® 100. Compatible with Astro® 430 and 320 for tracking only. Rugged and water-resistant to 10 meters, the tracking and training dog device with collar is tough enough to run wherever your dog runs, up to 9 miles away. The stimulation features let you train each dog separately — traditional stimulation allows you to make quick changes (low, medium or high) within a predetermined stimulation level (1-6), whereas linear stimulation allows progressively more stimulation from levels 1 to 18. You can remotely operate the LED beacon lights, built in to the dog device, to help locate your dog in low-light conditions. TT 15 ships with a 1-inch red collar strap. Replacement straps are available in multiple colors (sold separately).