If you purchase a Dell 4210 Server Rack, it is designed to have Dell Powerstrips installed. Likewise if you purchase an APC Server Rack it is designed to have APC Powerstrips installed. The APC Powerstrips are designed to install into a keyhole cutout in the back of an APC Server Rack. It is possible however to install an APC Powerstrip into a Dell 4210 Server Rack by utilizing the small set of L Brackets that come with the APC Powerstrip. The following images show how this is accomplished.
In the first image, you can see how the self tapping screws used to secure the L Bracket to the frame of the Dell Server Rack.
In the second image , it shows the APC Powerstrip installed to the server rack. You can also see how the Cable Management Bracket is installed on the APC Powerstrip.