NO MORE CALCULATION GUESS WORK? Doors are generally sized 12″/16″/18″/20″/24″/30″, you just need to pick our corresponding size of track. SPACE SAVING? Ultimate Space saving design, can be installed in any space, checkroom, kitchen, storage room, stairwell. Consider our folding door hardware, when you don’t have a location that provides ample sliding space for your sliding doors. HEAVY DUTY CONSTRUCTION? Solid steel, fine black powder coated surface, anti-corrosion ensures years of beauty and longevity. 8.8 grade self-tapping screws and roller screws ensure our hardware kit can hold two 220lbs doors. Over 15000 times test, bearing rollers slide like butter, slide quiet and smoothly. DOOR WEIGHT CAPACITY? 360 LB, fit max 4 doors leaf width 20″, max door opening 78″; The height from top of the door to the top of the roller is 5 7/8″, Thickness: 1-3/8″1-5/8. All nylon wheels have been tested beyond 100,000 rolls. STEP BY STEP INSTRUCTION? Precise instructions, step by step how to install we have written in the instructions, graphic elaboration, so that you do not have any confusion in the installation process. AFFORDABLE PRICE AND 24 HOURS ONLINE SERVICE? With almost half of the market price, you can get the premium quality products from us! PACKAGE CONTENT? 42 track X2, Spacer X6, Floor guideX2, HingeX6, Fixed rollerX2, Bifold rollerX2, Fixed roller lock bracketX2.