Abstract: A blower box for thermal prestressing of glass panes, includes a stationary part having a cavity and a gas feed line connected to the cavity, and at least one closure element having a plurality of nozzles connected to the cavity for applying an air flow to a surface of a glass pane, wherein the at least one closure element is connected to the stationary part at least via a connection element of variable length, and the at least one closure element is movable relative to the stationary part such that the distance between the closure element and the stationary part is variable, and the blower box is equipped with a system for moving the at least one closure element.