The flextone design gives this call natural sound and the ability to change volume and tone. * This easy to use call is deadly on Redheads, Cans, Bills, and Ring necks. * Just squeeze the end for the deeper tones of Canvasbacks or Redheads. * Leave the bell open for the higher pitch of Ring necks and Bluebills. * You can also mix it up to sound like a whole raft of divers.