Featuring a wide reed plastic barrel and the tone cap with automatic Lip Positioner. Placing your fingers over the holes while blowing will create a deeper sound with less volume. Remove your fingers from the holes to create a louder higher pitched sound. Makes locater challenge or invitation howl along with lost mate sounds. Includes the new V.E.T.T. system to create more volume stabilizes higher notes get raspier barks and takes less air to operate. #404 - The V.E.T.T. system contains a spring tuned to the precise dimensions that is located in the front section of the call. The spring helps create more volume stabilizes the higher notes maintains higher pitches and takes less air pressure to operate while blowing into it.