A printing unit with a cylinder which contains a functional layer (23) and has a supporting body (1) which passes through the cylinder and on which there are provided two ends (2, 5, 25) which support a sleeve (3) that accommodates the functional layer (23), and the supporting body (1) is supported in supporting elements (10, 11, 13) on the frame side, wherein the sleeve (3) can be centered in relation to the axis of rotation (8) by centering faces (6, 7) formed on the ends (2, 5, 25), at least one end (2, 5, 25) being detachable with respect to the supporting body (1).