Featuring 3 diaphragm calls to produce a variety of cow and bull vocalizations, the Phelps Beginner AMP Diaphragm Elk Calls 3-Pack is a must-have for early-season elk hunters. The AMP black elk diaphragm call produces high- to medium-pitched cow sounds and is great for mimicking a raghorn bugle. The grey call is an all-around performer that lets you produce mature cow sounds and ringing bugles. The green call is another great all-around call with a slightly stiffer reed than the grey call. Comes with 3 diaphragm calls Black call is super-easy to use Grey and green calls are excellent for all-around use