The top label is equipped with an inscription in the form of a barcode and a model number. A recess, which continues in two channels also implemented in the bottom label, is provided in the bottom label where the gas exchange opening is located when the label is used as intended. The top label covers the channel system. The channels discharge into the surroundings at the label edge, so that two gas passage openings are defined by the intersection region between label contour and the contours of the channel system. Liquid may drain out of the channel system in many different spatial orientations of the housing which the label is stuck onto as intended. A gas permeable membrane may advantageously be positioned in the region of the recess and extending somewhat over it. The membrane may also extend over the entire bottom of the label. If the membrane is implemented as self-adhesive on the bottom, it must then be largely free of adhesive in the region of the gas exchange opening in order to ensure its gas permeability.