Dairy ,The Gametraker is a cheesy little unit that suposedly works off of heat.Years ago I was desperate to find a deer I had shot.I searched and searched and finaly thought that I would go to a local sporting goods store to buy one,because of that sick feeling that I had.I looked for many hours,before deciding to buy this danged thing.Anyhow all it did was take me to areas where the sun had warmed trees and stuff like that.It seamed like a gimmic to me.I have learned alot since then and hope to never ,ever lose another animal again.I now have a dog that I will be training that is supposed to be an excelent breed for blood trailing,not that I ever plan on it ever happening again..