The door in the form of a trapezoid – not architectural elements and a simple and elegant solution to the problem of automatic closing doors that do not require a single additional detail. Instead of springs, hydraulic, pneumatic and even electronic devices works here… gravity. When opening such a door with a tilted axis (rotation its) center of gravity rises. Is to let go of the flap – the center of gravity will tend to occupy its original position, the door will slam shut.