The universal airlocks MPSK-LP are used for the product feeding and discharge of free- flowing, coarse- to fine-grained bulk materials up to a maximum pressure differential of 1.5 bar. The tangential arrangement of the inlet and outlet as well as those diagonally to the cells standing feeding edges prevent a cutting or a clamping of the material to be conveyed, even if from the full one delivers. This permits a high product throughput at quiet running art and long service life.