Black Roller–High quality steel. Door Max Weight Capacity: Up to 330lbs every pair rollers. Fits sliding Door Thickness: From 1 3/16″ to 2″. The top of the Doors to the ceiling : Min distance is 5.5. Our Product Sprcial Design. ·Carbon Steel Roller – Super load-bearing capacity, inner nylon wheels, will not wear the track when rolling. ·Adjustable Screw – The roller screws can be adjusted freely in any size within the door thickness from 1 3/16″ to 2″. ·Anti-jumpers – The little round discs won’t allow your door to be lifted off the rail. ·Door stoppers – unique spring design: Spring door stoppers plays a buffer role, reducing the noise of the collision when opening and closing the door. ·Floor Guide – Adjustable, can suitable for door thickness in. 1 3/16″ to 2″. And wall-hounted, don’t need to groove on the door bottom. ·Wooden plug: Insert wood plug in the hole, the hole diameter won’t enlarge, which stabilizes the nail into the wall, keeps whole system runs stable. ·Step by step Instructions: Every step has been precisely measured in practice and detailed dimensions are written. Door Stop: 2 PCS. Accoding to rail holes. 1 hole need 1 set. Only sliding door hardware kit, don’t include the Door. How to Choose Track Size. Track’s length should be twice of door panel’s width (like your door width is 2FT, You will need 4FT hardware Kit).