The IBM BladeCenter Memory and I/O Expansion Blade is an optional expansion unit for the BladeCenter HS21 Type 8853 blade server. The Memory and I/O Expansion Blade provides up to four additional dual-inline memory (DIMM) connectors for use by the blade server. It also supports installation of standard-form-factor, small-form-factor, or high-speed I/O-expansion cards.
See the IBM BladeCenter Memory and I/O Expansion Blade Installation Guide for more information.
Go to http://www.ibm.com/systems/bladecenter/hardware/expansion/ for more information about expansion units.