Swampy it's a Buck Gardner "Squirrel Call". I bought it several years ago and I have watched squirrels come to me from close to a hundred yards away. You have to camo up and they pickup pretty quick on movement, but I wait until they are close, and when I can't see them, they can't see me, and that's when I get ready to take the shot. Most of the time, they NEVER see me. Once they get close don't call when they can see you, or they will bust you.
Here is a pic (I hope) of the call, the load I use, and the rifle I use. It's a Model 92 Winchester clone I tuned myself, in 357 mag. loaded with a very light load 38 special cast bullet. The top rifle is the Model 92.
The call comes with a cd, and it is about as basic as you can get.