Two hinged boards, covered with leather or rubberized cloth. Smaller bellows (often called pneumatics) perform a mechanical function by collapsing or opening when connected to suction or pressure, respectively. Pumping bellows, (sometimes called feeders) powered by a crankshaft and connecting rods, are attached via one-way valves to spring-loaded reservoirs that store suction or air pressure. Manifolds or distribution boxes act as connecting points for the tubing that conducts suction from, and air pressure to, pneumatic-operated mechanisms, organ pipes, accordions, etc.