The folding NSDX is a door suspension system that is made of steel and zamak. Its purpose is to absorb the fall of the door and the shock of the closure. The lowering speed can be adjusted by one screw. It has a duration equivalent to 50,000 opening and closing cycles. Do not include the latch for the door. The minimum recommended height for the door is 300mm and this piece is the left arm. Each package contains a total of 20 units with a nickel-plated finish. Includes assembly instructions for all compasses available.