The Duel Stretchback Grunt Deer Call has adjustable sound - Stretchback allows you to instantly change your call sound by extending the rubber flex tube. This allows you to sound like a small buck, a big buck or a moving buck. It also allows you to make all types of buck grunts. The rubber flex tube is made out of a special rubber that not only produces the robust, most realistic call sounds but also perfectly grunts when you extend or contract the call. It's FreezeFree design allows you to call all day without freeze-up. Made in USA.