http://www.youtube.com/watch?v=dF4ya60NYV0
http://www.youtube.com/watch?v=Sa4MfyQ6I0o
Looks like they work. I only use fixed heads so this is all for you "other guys"
Edit:
I have no problem with killing an animal in a fence that is going to be eaten with a bow. My dad has a 1/2 grown calf (black angus) that is refusing to corral up and go to market. I wish he would just send me and my bow to end the trouble and afterwards we just take him to the locker. More fun than using a .22 bullet to the brain and you get to try out your archery equipment on it. This is a product testing.