For cow calling, or bugling for that matter, I started with and still prefer a diaphram call for elk. The one I like is the Perfection Double Reed Turkey call (blue) for cow calls and the triple reed (brown)can belt out some great bugles. I use it with a grunt tube ( aprox 2" dia. and a little over 2'long section of Shop-Vac hose))for more resonance or with out when things get up close, although if I'm calling for someone else I can still use the tube, but otherwise the hands free use is mighty handy plus. Diaphram calls are a good bit more trouble to learn, when I first tried I drooled like a rabid dog plus the neighbors dog would come and sit next to me and howl along, but I really think they're worth the effort. I make my own open reed calls for coyote howling, different distress etc. and they work pretty darn good, but I still prefer the diaphram on elk.