3 cm) (two- or four-post EIA cabinet or rack, with mounting rails that conform to English universal hole spacing per section 1 of ANSI/EIA-310-D-1992). For more information, see Requirements Specific to Perforated Cabinets. AudioRax Rack Rail Pair, Cut-To-Order | 1/2U Spacing EIA-310 Standard The EIA-310 standard has served as the foundation for 19-inch equipment racks for over five decades. It defines the. Standardization in rackmount systems is essential for ensuring equipment compatibility, optimal space utilization, and global product interoperability. These measurements define how devices are positioned vertically and horizontally within the rack structure. Standardized spacing ensures that servers, switches, patch panels, and.