The invention relates to an application unit for directly or indirectly applying a liquid or pasty medium (4) to a continuous material web (6), particularly one made of paper or cardboard, having two gap limiting walls (13, 14) that are spaced apart from one another, are each formed on corresponding lip members (2, 3) and between them define a metering gap (12) for the liquid or pasty medium (4), and having a gap-width adjustment device (8, 9) mated at least with the one lip member (2). There is provided on at least one gap limiting wall (13) an elastic adjustable wall member (7) which can be expanded into the metering gap (12) relative to the gap limiting wall (13), extends across the length of the metering gap (12) and can be actuated by the gap-width adjustment device (8, 9).