Here's a link to the World Championship, I used the ELK power howler for my barks, lone howl, and threat bark howl...
**calling tip- turn it upside down from what the directions say and IMO, sounds much better. I can use it both ways now but when I was learning to use it, it made it a lot easier by rotating it 180 degress. I think it sounds better, seems like you can adjust air pressure much easier. hope this helps.**