Primos Pro Mallard Polycarbonate Duck Call - Green The Pro Mallard single-reed design makes this call an easy-to-blow call. It features a tuning hole in the bell or stopper, which allows you to change the pitch of the call and sound like two different ducks. This call can be used with very little air pressure. You wont wear yourself out blowing this call. Features: Easy blowing single-reed call Blows when wet! Sounds great in timber or over open water Made with .010 Mylar reed for raspy quacks to clear high calls Tuning hole in the bell lets you change tone and pitch