Electronic collar used for training. Here is a link that is pretty educational: www.gundogsupply.com/dog-training-collars-buyers-guide.html
I use the ecollar of working with my dog from a distance like with the recall or field work. They are also used for snake proofing in areas where we have poisonous snakes.
Thanks for your answers. I thought that's what it was. I considered getting one for Baira. She is generally very good, comes back when called, at least on the 3rd or 4th call anyway but twice now she has gone after a rabbit and no amount of screaming in the world was distracting her from the damned rabbit. I thought people would be shocked (no pun intended) if I said I was thinking of using one but I guess it's used more than I think. I would just like her to come to me on the first call and i'd like to be able to stop her when she's on the run after something. I haven't been able to find one for sale here and i'm beginning to wonder if they are available. What is the best type to buy?