Stopper for a box-type container with air admission, having: - A mouth , - a stopper , - and a seal attached to the mouth and the stopper by means of a precut, the seal having a tongue for pulling on the same and tearing off said seal by breaking the precut joining the stopper and the seal as well as the precut joining the seal with the mouth ; - the mouth having a flaring or base for gluing the cardboard of the box-type container; - the stopper having a clip for closing, for being arranged on the mouth like a perimetral catch which, by bending of the plastic material of the stopper , allows opening and closing the mouth by gripping, wherein - the stopper has in the back a cutting part characterised in that the cutting part is with toothing along the entire front edge thereof, and in that the stopper has in the back a pushing part , wherein the stopper is having fingerprints on both sides thereof for greater extraction comfort; - and in that the stopper for a box-type container has a movable part closed on the sides by partitions forming a box closed at the front part thereof by means of a closure with toothing along the entire front edge thereof, movable along the interior of the mouth by means of strips inserted into guides , this movable part being insertable in the mouth portion when pushed by the pushing part of the stopper to penetrate into the container and to form a passage for the air during outflow of liquid, the movable part generating inside the mouth an upper part for the admission of air and the cutting part generating a lower part for the outflow of liquid through the mouth glued to the box with adhesive , the outflow of liquid through the lower part being compensated with admission of air through the upper part at the same time and in the same amount. - A mouth , - a stopper , - and a seal attached to the mouth and the stopper by means of a precut, the seal having a tongue for pulling on the same and tearing off said seal by breaking the precut joining the stopper and the seal as well as the precut joining the seal with the mouth ; - the mouth having a flaring or base for gluing the cardboard of the box-type container; - the stopper having a clip for closing, for being arranged on the mouth like a perimetral catch which, by bending of the plastic material of the stopper , allows opening and closing the mouth by gripping, wherein - the stopper has in the back a cutting part characterised in that the cutting part is with toothing along the entire front edge thereof, and in that the stopper has in the back a pushing part , wherein the stopper is having fingerprints on both sides thereof for greater extraction comfort; - and in that the stopper for a box-type container has a movable part closed on the sides by partitions forming a box closed at the front part thereof by means of a closure with toothing along the entire front edge thereof, movable along the interior of the mouth by means of strips inserted into guides , this movable part being insertable in the mouth portion when pushed by the pushing part of the stopper to penetrate into the container and to form a passage for the air during outflow of liquid, the movable part generating inside the mouth an upper part for the admission of air and the cutting part generating a lower part for the outflow of liquid through the mouth glued to the box with adhesive , the outflow of liquid through the lower part being compensated with admission of air through the upper part at the same time and in the same amount. <EOS>