An intermediate piece includes an upper element and a lower element, and a check valve including a head and a spring element exerting an opening pressure on the head. The check valve is arranged between the upper element and the lower element at the first or second passage and is configured such that a first or second passage can be closed by the check valve and such ay that the first or second passage is opened when a dispensing pressure counteracting the opening pressure is applied at least at the respective flowable component.