Field glossary

RU / U

Rack unit, 1.75 in of vertical mounting height; an open U is a recirculation path without a blanking panel

Used across 2 Anvilfield field guides, most in Datacenter.

Also defined as

Rack unit, the vertical mounting increment of 1.75 in (44.45 mm) on a 19 in EIA-310 rack
Rack unit, 1.75 in (44.45 mm) of vertical mounting height on a 19 in rack

Where this shows up