If you are a duck hunter, this is an easy call to run (simply do a feeding chuckle into the call and use your hand to control back-pressure)...
My duck hunting buddies can run this call easy, while my non-duck hunting friends cannot run it to save their lives...
Personally, I took the idea of the Haint and found an old squirrel call (actually not sure what it is) but it has a better tone, and it sounds better than the production calls to me...