Main Material: High quality carbon steel .Black frosted, corrosion protection

The distance from the top of the door to the ceiling should be at least 8 inches

Fit for door panel thickness:1-3/8" to 1-3/4".Door Max Weight:200lbs

Usually, we recommend the track length should be at least 2 times the doors width or the opening.For example,if the door is 30'' wide.

You will need 2 * 30'' = 60'' long track. Or if you have an opening that is 30'' wide, you will need at least 60'' long track.

All tracks are pre-drilled holes, the spacing between each hole is American standard 16''.

Tracks 7.5 FT and under are one complete track, 8 FT and above are connected by multiple shorter tracks,

There are connection holes to expand the track at the end of both sides, therefore, the spacing between the holes in the connecting section may not be 16''

Packing list：Track; Roller; Spacer；Floor guide；Anti-jump pads；Door stopper；Connector.

Only the hardware, door not included.Warranty : 5 years