A relay rack for supporting electronic components having a swinging door frame with a simple mechanism for selectively opening either left or right hand sides of the door frame while preventing inadvertent simultaneous release of both sides. The relay rack comprises a top frame, a bottom frame, a rectangular door frame, and four pivot pins on the door frame. Recesses in the top and bottom frames receive the pivot pins. Latching bars are mounted to the top and bottom frames for sliding movement to the left and to the right relative to the frames for holding or releasing the pivot pins from the recesses so the door frame can be swung open and closed about either a left or right vertical pivot axis. The top and bottom frames are releasably fastened to the back frame to permit removal and replacement by different top and bottom frames whereby a front-to-back dimension of the rack may be readily changed without replacing the back frame or the door frame.