The True Double II is part of our Piggy Back series meaning it has a stacked double frame with one thin prophylactic reed in the top frame and two prophylactic reeds in the bottom frame. Both frames are separated by 1/16 inches, which doesn't allow the reeds to stick together. The True Double II has a slightly higher pitch than the True Double (model No. 108). The True Double II makes raspy yelps, clucks, cuts, and cackles.