The minimum internal width between the rails must be 17.72 inches (450 mm) .
Specifies standard fastener systems, typically using #12-24 or M6 screws and cage nuts . Evolution and Compliance Eia Eca-310-e Pdf
used in data centers, telecommunications, and audio equipment. While the full PDF is a copyrighted document typically purchased from IHS Markit The minimum internal width between the rails must be 17