DIYHD Stand Up Black Rolling Library buying Hardware,Tensible Sliding Roller(No Ladder)

Only hardware,not including ladder
If you want ladder, please go to this link: https://www.etsy.com/listing/964805850/diyhd-unfinished-rolling-library-wooden

Material:Steel + Aluminum,Surface:Rustic Black
Hollow Track Thickness:2mm;The brackets were welded together with track;The length between two brackets is 19-11/16"
Tensible roller,the ladder can be stand up when not working

Tube diameter:1"(25mm);
Thickness:0.118"(3mm);
The length between 2 bracket:19 5/8"
Bracket length 3 /18";Screws for bracket length 1 1/4";
Make sure the place where you install the track have at least width:3 1/8";thickness 1 1/4" for installation

[39-3/4" full set hardware] including:
Top roller*2pcs;
Floor roller*2pcs;
39 3/4" round tube with 2 bracket*1pcs;
Stop*2pcs;
End cap*2pcs;
Screws*1set
6.6FT is 2 39 3/4" tracks with 1 track connector;
10FT is 3 39 3/4" tracks with 2 track connectors;
13FT is 4 39 3/4" tracks with 3 track connectors;

[4FT full set hardware] including:
Top roller*2pcs;
Floor roller*2pcs;
4FT round tube with 2 bracket*1pcs;
Stop*2pcs;
End cap*2pcs;
Screws*1set
8FT is 2 4ft tracks with 1 track connector;
12FT is 3 4ft tracks with 2 track connectors;
16FT is 4 4ft buying tracks with 3 track connectors;
20FT is 5 4ft tracks with 4 track connectors;