The lower rail was constructed with the lower rail for car center only. As the school consisted of specialized departments, many machines and equipment were moved, so it was built with a lower rail dedicated to a car center that was more solid and durable.

Added middlesbars to places that were slightly higher than normal folding door heights. A high folding door height increases the risk of breaking the glass as a single glass becomes longer.

So, if the height is high, the middle bar is placed in the middle of the glass rather than one, and it is constructed in two pieces to prevent glass.