The QuadGrunter XT features an adjustable o-ring which gives it the versatility of four calls in one; simply move the o-ring along the soundboard inside the mouthpiece to project mature buck grunts, young buck grunts, doe bleats or fawn bleats. The expandable bellow on the end of the call allows for ultra-realistic tonal inflections to make your calls sound like they are coming straight from the lungs of a real deer on the move.