These are just some notes regarding Data Cener Racks:
open bay rack = 2 post frame rack
close bay = wrightline
guide rails
network racks, shorter
server rack longer
1 u = 3 holes
47 u hight
42 u rack
Good information:
https://www.anixter.com/content/dam/Suppliers/Tripp%20Lite/White%20Papers/Rack-Basics-White-Paper-EN.pdf