Abstract: Valve unit (1) intended for puncturing a film (P), especially a plastic film, thereby creating a tight lead-through through the plastic film (P), which valve unit (1) comprises a first member (2) for puncturing the plastic film (P), which first member (2) has a hollow space (5a) and at least one opening (5) leading through between the outside of the first member (2) and said hollow space (5a), and further a second member (3), which is intended to be positioned on the side of the plastic film (P), which is opposite to the first member (2) when the valve unit (1) is attached to a plastic film (P), said hollow space (5a) being in open connection with the surrounding atmosphere through the second member (3), a groove (7) extending around the circumference in the area between the first and the second members (2,3) being disposed to receive the edge portion of the plastic film (P) around the valve unit (1), which has been pricked through the plastic film (P), and an annular, resilient element (12) being displaceabl