[EXCELLENT QUALITY]: Bi-folding door kit is made of high quality carbon steel with a matt black finish, ensuring the product is corrosion, water, fire, rust-resistant, durable, and maintains its beauty and longevity for many years. [PRODUCT DETAILS]:4FT/48"track, Each door panel should be half the size of the door opening + 50mm (1.97") and the track should be more than 150 mm (6") wider than the door opening, thickness: 1.18''-1.58'', leave 6" from the upper edge of the door to the roof. [PACKAGE INCLUED]: splicing track, 2 J-type pulleys, 1 rotating shaft, 2 anti-jumping discs, 2 door stops, 1 floor rail, all hardware needed for hanging door. Note that there is only hardware, [DOOR NOT INCLUDED] [QUIET AND STABLE]: The roller part is made of high-quality nylon material, which ensures that the roller slides like butter on the track. There are high-quality spring limiters on both sides of the track to ensure that the door is fully cushioned when it is closed, and the door will not be damaged. [LIFE-TIME AFTER SERVICE]: 100% refund and return, no matter if you encounter any problems before and after the purchase, please feel free to contact us 24 hours a day, we will definitely actively solve the problem for you.