Dell EMC PowerProtect DD9900 - Attach Outer CMA Bracket to the Rails

Figure 10 Attach outer CMA bracket to the rails
2. Align the hole of the inner bracket and push down to attach it to the rail.
Note:
Some pressure is required to push the inner bracket down and secure it. The
bracket clicks when it locks in place.
Install the System in the Rack
24 Dell EMC PowerProtect DD9900 System Installation Guide