Siemens CAB2-RD Two-Row Inner and Outer Door SetThe Models CAB2 BD RD and CAB3 BD RD Enclosure Doors from Siemens Industry, Inc., are used with the CAB2 BB RB and CAB3 BB RB Enclosure Backboxes. Two doors, an outer and an inner, are required for each enclosure. The CAB2 BD and CAB3 BD outer and inner doors are black; the CAB2 RD and CAB3 RD outer doors are red and inner doors are black.