Rocky Mountain Calls Yote Howler Diaphragm Call combines a dynamic mouth call with a powerful amplifier tube for long-distance coyote-calling performance. Employing the V.E.T.T. system, this predator call contains a spring tuned to exacting dimensions inside the adapter. This helps create more volume and tone consistency. It also helps stabilize higher notes, which gets raspier barks, and it takes less air to operate. So go ahead, start creating lifelike howls, barks, yips and all the canine sounds needed to lure crafty coyotes into shooting range. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Game Calls.