Abstract: Dosing unit comprising a dispensing device and a container bag unit. The container bag unit has an imperforate wall. A sleeve-shaped part having an opening therethrough is secured to the wall, the wall closing one end of the sleeve-shaped part. A piercing element with a point is disposed within the sleeve with its point directed toward the wall. A dispensing device is receivable in the end of the sleeve-shaped part opposite the wall to engage the piercing element and to move the piercing element relative to the sleeve to pierce the wall to permit flow of the contents of the bag unit through the sleeve-shaped part and to and through the dispensing device. The piercing element is fixed to the sleeve-shaped part by a rupturable connection that breaks when the dispensing device presses against the piercing element.