Ed, I use D.T. Systems EDT 102 collars. DT Sytems is a fair sight cheaper than Innotek and Tri Tronics for about the same range 1/2 mile or so. You can by more expense from all three mentioned above that have greater range, up to two miles, but you will pay for them. Of course you do get what you pay for. Consider a two dog version/ or three dog model if your working with more than one dog at a time. One transmitter works two or three reciver collars. One thing to consider is where the controls for the intensity levels are. Some are at the collars and some adjust at the hand held transmitter which I prefer because I can quickly adjust the intensity level in the field if necessary.

Enjoy, Juniorpc