Abstract: The invention comprises a frame (2) secured to a container and a movable body (3) articulated with one end of the frame (2) by means of a hinge (4) formed along a common edge of the bodies articulated therewith, said movable body (3) having two side walls (6) and a front wall (7). The invention is characterized in that both ends of the upper inner edge (2c) of the frame include a pair of flexible tongues (17) which, in the closed position, engage with respective recesses (10a) on the upper edge of the side walls (6) of the movable body (3) and on the end adjacent to the front wall (7). The movable body (3) and the fixed frame (2) include a cavity (12) next to the hinge (4), said cavity allowing the movement of material in the closed position. The invention provides an improved sealing and closure system.