H.S. Strut Tone Trough Turkey Diaphragm Starter 2-Pack -Hunters Specialties' new line of H.S. Strut(R) Tone Trough diaphragm calls are great for beginners as well as experienced callers. The calls feature a raised dome that forms a tight seal in the roof of the caller's mouth. The Tone Trough(TM) creates perfect pressures for realistic hen sounds. The calls are built with a Premium Flex(TM) frame and Infinity Latex(R) for consistent tones. New Infinity Latex - requires less air pressureDouble D utilizes 2 thin reedsRetains shape for long term perfect calling pitchTone Trough call - directs air over the reeds for easier, more consistent callsRaspy Old Hen design - 2-reed call with double split top reedDouble D utilizes 2 thin reeds