For Free-Stand Enclosures, Type 12 (Bulletin A30), Free-Stand Enclosures, Type 4 (Bulletin A4L) and One-Door Free-Stand Fiberglass Enclosures, Type 4X (Bulletin A17). Pairs of full-length or half-length rack mounting angles are available for mounting 1 9-in. (483-mm) and 24-in. (610-mm) rack-mounted equipment. Type RP rack mounting angles are 10 gauge steel with mounting holes tapped #10-32 thread and spaced per EIA standard RS-310-D universal spacing. Angles and mounting hardware are plated. All mou nting hardware is furnished.