Connecting RPS720 External Redundant Power Supply to DELL 5548

HI, 
We have two DELL 5548 network switches.
As per the switch manual, we can buy the RPS720 External Redundant Power Supply connecting to current DELL 5548 network switches to achieving the redundant power supply.

My question is how to connect this RPS720 External Redundant Power Supply to the existing DELL switches?

Do i only purchase the RPS720 External Redundant Power Supply which including the power cable connecting to existing switch or i need to purchase any item to achieve this?

I try to search the internet but it is quite less information regarding on this.