The RackSolutions Dell PowerEdge R210, R220 Slide Rails are an upgrade over the standard Dell R210, R220 rail kit, as Dell''s rails do not slide. RackSolutions'' model is also compatible with round, square or threaded server racks. Versatility is ingrained into every aspect of the RackSolutions Dell PowerEdge R210, R220 Slide Rails'' design. They feature a mounting depth ranging from 3" to 30.5", an extension range of 17.5". These rails are an alternative to the Dell R210, R220 rails. The slide rails are built with high-quality design principles applied to a stainless steel frame. The slides themselves feature ball bearing construction to ensure smooth and stable functionality. These rails may also be installed in a 2 post center mount configuration (P/N: 120-2245), 2 post flush mount or 4 post configuration (P/N: 120-2382). The RackSolutions Dell PowerEdge R210 Slide Rails will ship with all of the necessary hardware for installation. As a result, buyers need only have a Phillip''s head screwdriver to assemble the product.