These are the EWI Tourcase tm Rack Panel Blanks. Currently they're available in 4 models:
1U (1.75") high
2U (3.50") high
3U (5.25") high
4U (7.00") high
These are basic metal rack panel blanks made from 14 gauge steel, suitable for filling empty space in conventional 19" racks or for drilling to make custom application panels. The panels feature a 0.25" top and bottom lip for added strength and finished appearance when placed against existing rack equipment. The length is 19" and the finish is matt black powder coating. Each panel comes with 4 rail screws and washers.