I' ve been using one for years. For me they seem to call in more does than bucks, but that is no scientific study. Silence it when you are not using it though. One time (at deer camp) I forgot. It was going of as I was climbing my tree, and next thing you know a doe comes running in looking at me as I am half way up the tree.

Two weeks ago I shot an 8 pointer and he would not respond to the can. He came right in when I grunted though.