Jupiter JTU1010 1000 Series Tuba - Key of BBbThe Jupiter JTU1010 4 Valves BBb Tuba is a smaller version of the model JTU1110 Concert Tuba. It features a . 709 inch bore with 4 front action piston valves for comfort and smooth performance. Specifications Lacquered Brass Body is produced using state of the art technology to ensure an instrument of the most accurate scale and playability Stainless Steel Pistons have remarkably smooth, fast action for improved agility and playability The Wood Frame