EMC CX3-10 Field Installation Manual page 6

Device height requirements
Table 2
EMC Rails and Enclosures (CX3-10 Class and CX3-20 Class Storage Systems) Field Installation Guide
6
The predrilled holes in the cabinet channels are based on the U
measurement. The holes are predrilled at distances of 1/2 inch, 5/8
inch, 5/8 inch (totaling one U), then 1/2 inch, 5/8 inch, 5/8 inch
(another U), and so on. On EMC 40U and 40U-C cabinets, the 1U
increments are marked by a horizontal line or small hole in the
channel. See Figure 3 on page 7
Table 2 lists the vertical space requirements of typical rackmounted
devices.
Height requirements of typical devices
Height
1U, 1-3/4 in, 45 mm
2U, 3-1/2 in,90 mm
3U, 5-1/4 in, 133 mm
4U, 7 in, 178 mm
on the next page.
Number of
cabinet channel holes Typical device example
3 CX3-10, CX3-20 and
CX3-40 SPS, CX3- series
SPE3, some switches
6 CX3-80 SPS,
some switches
9 EMC DAE2P, DAE3P
12 CX3-series SPE2