The bone Collector Series- Bull Collectorwas designed to make all elk sounds.It's Myler reed system allows you tobugle like big bad herd bulls or sound likesmaller satellite bulls by simply adding ordecreasing both air flow and pressure onthe reed. The expandable tube also aidsin creating the perfect tone by extendingor shortening the tube. When it's time tocow call, simply pop off the mouthpieceand you are ready to mew like a cow, chirplike a calf or do aggressive estrus cries ofa hot cow in heat begging for companyfrom the herd bull.