The Phelps Unleashed Elk Bugle Tube was designed with thick walls for loud volumes and no "plastic" sound. Corrugations provide structure to the tube and help provide great resonance. FeaturesLarge corrugations in the chamber provide great resonance.Corrugations provide structure to the tube1.25" flared mouth opening for comfort and usability.Over-Cupped Exhaust Bell for backpressure and resistance making it easier to use ALL diaphragms.Thick walls for extreme volume and NO plastic sound.