Sealing device, and a packaging container

A sealing device for forming a transversal seal to a tetrahedral packaging container, comprising:

• a sealing element configured to provide a transversal seal to a packaging material of the packaging container;
• an imprint ruler arranged at a longitudinal distance from the sealing element, and
• a flattening section arranged between the sealing element and the imprint ruler and configured to flatten a portion of the packaging material having a perforation,
• wherein the imprint ruler protrudes from a surface of the sealing device relative to the flattening section by a protrusion length, and is movable relative to the flattening section such that the protrusion length is adjusted thereby providing an adjustment in length of the packaging container formed by the packaging material, and
• the imprint ruler is configured to provide a transversal imprint to the packaging material by compressing or folding the packaging material such that the portion having the perforation is arranged between the transversal imprint and the transversal seal, and such that the transversal imprint forms a barrier for content in the packaging container.