The readyrails sliding rail kit for 2u systems including the poweredge r520 r720 and r720xd provides tool less support for racks with square or unthreaded round mounting holes including all generations of dell racks they also support tooled mounting in 4 post threaded racks via an optional adapter brackets kit the optional cable management arm cma can be mounted on either the left or right side of the sliding rails without the use of tools for fast and easy deployment