23-inch racks use evenly spaced mounting holes. Although it is called a 19-inch rack unit, the actual mounting dimensions of a 19-inch rack unit are 18 + 5 / 16 in wide, center to center.

Rack units are universally the same, but the type of thread can vary depending on the rack. Mounting rails can be No. 10-32 tapped (Unified Thread Standard), No. 12-24 tapped, metric M6 threaded or universal square holes. Universal square holes are becoming the most common as these allow the