Abstract: A clip-closure (1, 2) for closing container systems made from film, comprising first closure and second closure part (4,5). A connecting device is provided for the securing of the second closure part (5) to the first closure part (4) in the assembled state. The first closure part (4) may be of U-shaped configuration and includes two limbs (7, 8). The second closure part (5) is of W-shaped configuration and comprises a central limb (6) as well as two side limbs (9, 10) spaced apart therefrom. A first part of the connecting device is provided on the limbs (7, 8) of the first closure part (4) and a second part of the connecting device is provided on the side limbs (9, 10) of the second closure part (5). The invention also relates to an opening tool (41).