RCB1065-2U 2U 23-inch to industrial standard EIA-310 19-inch Rack Reducer for 2-post or 4-post rack cabinet (1 Pair) Fits into any standard EIA-310 23" 2-Post or 4-Post racks. Specially designed for mounting 19" rack equipment in a 23" wide rack cabinet 2U Height, One end with oblong holes for #10, #12 or M5 rack screws, other end with square cage nut holes for #10, #12 or M5 Cage Nuts. Including mounting hardware