I use one on squirrel dog, and it is very helpful, especially down in southern Ohio in the hills. is nice to know exactly where dog is when he is 800 yards and three ridges away. you can find them used in servicable condition. that's how I got mine. bought both Astro 220 receiver and DC 30 collar used. I have a little over $300 in the whole thing. if I were starting over, I would have gotten the Garmin Alpha. combination shocking collar/gps tracking all in one. Tritronics classic 70 shocking collar is over $300 new, and I just got one. for a few dollars more I could have had an Alpha. lots of guys dumping their old collars and going to the Alpha system. search google and you'll find use collars/receivers for half the cost of new, perhaps less.