The automatic threshold of Domatic — is a mobile sealant with the start button located from a door Hinge. When closing a door there is a pressing a start button. Thus the threshold falls and densely adjoins to a floor. Thus, the gap between a floor and a door cloth is hermetically closed. When the door is open, the automatic threshold is completely hidden in a cloth. When opening a door impact on a start button disappears and the threshold rises.