Construction physics: absolutely tight thanks up to four tightening levels. Pneumatic seals do not let any air through. The inner seal is used as a standard, a cleverly devised system of press and labyrinth seals on the outside provides draft-free comfort. The seals are blown up automatically through a control pulse. Brush seals remove the coarse dirt and they display an aesthetic transition from the frame to the leaf. The hot air duct, which can be installed shapely into the floor is recommended for the compensation of the missing heat reflection of the glass.