Abstract: “DEVICE INSERTED INTO THE SEALED LIDS OF METAL PACKAGING FOR LIQUID PRODUCTS”, comprising a fixing system obtained through a process of crimping to the upper edge of the metal package (1), preferably made of tinplate, characterized by an assembly comprising a plastics membrane (2) and a metal ring (3) stamped to form a flat inner cross section (4), which has a central circular opening (5) with an inner edge turned downward and folded inward (6), and an elevation to form a lower seat (7) which is surrounded by a peripheral rim facing downward and slightly inward (8) to enable crimping together with the aforesaid membrane (2); the peripheral edge (9) which is inserted into the seat (7) for crimping onto the edge of the packaging (1), followed internally by an annular recess (10) into which the flat inner cross section (4) of the metal ring (3) with the inner edge turned down and folded inward (6) is inserted, this being followed internally by a perimetral annular reinforcement (11) and with the lower triangular