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Zeros patented automatic door bottom technology ensures an efficient seal against the floor or saddle. As the door is closed, the adjustable plunger is compressed against the door frame, activating a concealed flat spring mechanism. This mechanism drops the seal smoothly from the housing in a scissor-like motion as illustrated below. The door seal compresses on either even or uneven surfaces and retracts automatically when the door is opened. All Zero automatic door bottoms function the same way. The concealed spring mechanism causes the insert seal to activate on the hinge side first. It prevents the seal from dragging along the floor or threshold while the door is being closed to avoid door hang-up or closing delay.