This assembly holds 4 - 551ESD Cabinets and 4 - 554ESD Cabinets which are included. Frame of semi conductive epoxy powder coated steel in light grey RAL 7035. 3 aluminum rails are included. With bottom shelf of .5" ESD-laminate. Four castors ? 3.94" which two are conductive and two braked. Load capacity 330 lbs. Overall dimensions D x W x H: 24" x 30" x 67".