B-Line Eaton series open racks, Aluminum, #12-24 mounting hardware, Rack width 23, Mounting spaces: 5, Flat black powder coat, Blank filler panel

It covers 5 mounting spaces, which is 5 rack units of open space in a 23 inch rack. The panel measures 8.69 inches in height, matching the 5U opening it blanks off.

The rack uses #12-24 threaded mounting hardware, so you'll want #12-24 rack screws. Count 10 screws for a 5U panel if you're fastening both flanges at top and bottom of each space, and confirm you have spares, since rack screws are not part of the panel itself.

Aluminum, with a flat black powder coat finish. Aluminum keeps the panel light (3.54 lb for the 5U size), which matters when you are hanging several blanks in a two-post open rack and want to keep loading down. Steel blanks are heavier and more dent resistant if the rack is in a high traffic corridor or shop area.

Order Eaton B-Line part SB5772305FB. That number covers the aluminum blank filler panel, 23 inch rack width, 5 mounting spaces, flat black powder coat, with #12-24 hole pattern.

Only partly. Blanking panels stop air short-cycling through empty rack spaces, but on a two-post open frame rack there is no front-to-rear containment to begin with. The main jobs this panel does in an open rack are covering unused spaces for a finished look, keeping hands and cables out of the gap, and dust control. If you are chasing real hot aisle separation you need an enclosed cabinet, not an open rack.

The panel stock is .09 in thick. That is a light gauge aluminum sheet, fine for covering open rack spaces, but it is not a structural or weight-bearing shelf and should not be used to support equipment.

It comes in flat black powder coat, which is the standard black finish used across the Eaton B-Line open rack line, so it reads consistent alongside black rack uprights and other black accessories. If your existing racks are a gloss black or a grey, the flat black will look slightly different in sheen.