This one-of-a-kind Garmin Astro DC 50 Dog Collar is compatible with the Astro 320 handheld GPS to pinpoint your dog's position and show you exactly where he is, even when you can't see or hear him. Strap the DC 50 wireless transmitter on your dog, and track his position on a handheld GPS device (not included). Adjustable signal transmits as often as every 5, 10, 30 or 120 seconds so you can see his current location and a trail of where he has been. Top-mounted GPS antenna improves performance via an integrated GLONASS positioning system that maintains location, even in heavy tree cover or deep canyons. Innovative bark-identification technology lets you know if your dog is barking, even if they are out of audible range. Rugged construction is waterproof up to 10 meters. System allows you to track up to 10 dogs at a distance of up to nine miles (line of sight) with the purchase of these additional collars. Powered by a rechargeable, replaceable lithium-ion battery.