Rack railsThe rail offerings for the R640 system consist of two types of rails—sliding and static.The sliding rails allow the system to be fully extended out of the rack for service. They are available with or without the optional cablemanagement arm (CMA).Figure 10. Sliding railsThe static rails support a wider variety of racks than the sliding rails. However, they do not support serviceability in the rack and are thusnot compatible with the CMA.Figure 11. Static railsOne key factor in selecting the proper rails is identifying the type of rack in which they are installed. Both the sliding rails and the static railssupport tool-less mounting in 19 inch-wide, EIA-310-E-compliant square hole and unthreaded round hole 4-post racks. Both also supporttooled mounting in threaded hole 4-post racks, but only the static rails, as the more universal solution, support mounting in 2-post (Telco)racks.930 Rack rails