Extra Dog Tracking transmitter for use with Astro System - to track multiple dogs. This rugged, all-weather collar has an integrated GPS transmitter and antenna that work with the Astro® 220 to ensure that your dog will never be lost again. Plus, it’s specially weighted so the antenna will always point to the sky for optimal signal. When teamed up with the Astro™ 220, this system will have you hunting in no time. The DC-30, in combination with the Astro 220, pinpoints your dog’s position every 5 seconds and runs for 17 hours. You can extend the battery life of the DC-30 by changing the position transmit rate from 5 to 10 or 30 seconds, enabling the DC-30 to work up to 36 hours in the field on one charge. You will know if your dog is pointing, sitting, moving or treeing. Where he’s at. Where he’s been. How fast he’s moving and how far he’s gone. Wireless collar transmitter. Goes where your dog goes - thick, tangled grass, dense foliage, overhead tree cover, No problem.