21" wide mounting rails are required for a NetShelter cabinet.
All versions and serial ranges.
Some telecommunications equipment is manufactured to ETSI standards which can require 21" wide mounting rails. This is not a current EIA/ECA-310-E width.
There is currently no 21” mounting rail kit available as an accessory for the NetShelter cabinets. The 21" width does not exist in the EIA/ECA-310-E specification. It comes from the the ETSI (European Telecommunication Standards Institute) standard, which allows for 19”, 21” and 23” mounting rail widths. If the opportunity involves 100 or more cabinets with 21" wide rails we can investigate a custom cabinet request. Please contact your APC supplier or sales rep to pursue a custom cabinet request.