Air filter and use of a filter element in an air filter

An air filter comprising:

• a filter housing;
• a first flat filter element and a second flat filter element, each comprising a filter medium body with an inflow surface and an outflow surface, wherein the first flat filter element and the second flat filter element are arranged in the filter housing;
• and
• a flow guiding device configured to selectively guide an air flow to be filtered through the first flat filter element and the second flat filter element in series or at least partially past the second flat filter element;
• wherein the outflow surface of the first flat filter element and the inflow surface of the second flat filter element are spaced apart from each other and together form a widening bypass channel;
• and
• wherein the filter medium body of at least one of the first flat filter element and the second flat filter element comprises an intrinsically changing height and has a reduced height in a region of a larger width of the bypass channel.