Rolling Thunder Game Brute XL Cutdown Game Call Ducks Frost. It has a 3" barrel the same size barrel as vintage P.S. Olt cutdowns. It offers a bigger exhaust a longer tone board and contains a step-bore system: a first for us at Rolling Thunder. These features allow more precise control in both sound and tone for experienced callers who can properly introduce clean air into the call. Specifications for Rolling Thunder Game Brute XL Cutdown Game Call: Manufacturer: Rolling Thunder Game Fabric/Material: Acrylic Species: Duck Package Contents: Rolling Thunder Game Brute XL Cutdown Game Call Rolling Thunder Game DC013CF: Brute XL Cutdown Game Call Ducks Frost