Rolling Thunder CORE MeanDuck J-Frame Duck Call, Acrylic, Sage Green The Rolling Thunder CORE MeanDuck is a j-frame duck call made in acrylic with a Sage Green color treatment. The named call design and material are the key distinctions of this version. The j-frame designation describes the call format. This is a dedicated duck call for waterfowl calling, with the CORE MeanDuck name distinguishing its specific design. The Sage Green treatment provides the visual identity of this acrylic version. Key Features Call design: J-Frame configuration. Acrylic construction: Acrylic call body. Color: Sage Green variant. Specifications Brand: Rolling Thunder Model: CORE MeanDuck Type: J-Frame duck call Material: Acrylic Color: Sage Green Shop the Rolling Thunder CORE MeanDuck J-Frame Duck Call, Acrylic, Sage Green at BattleHawk Armory.