Chief Mfg.Rack Hardware Mount Black (NS1F4123) S1 racks are designed with a base that holds the rack rail in place during assembly to greatly simplify and speed up the assembly process Covered vented bottom panel provides additional space for mounting components, but can be easily removed for cable entry Optional branding panel keeps your Brand out front of the rack door Laser cut knockouts make conduit and cable installation a breeze Dual 3U panel in the top works with any standard 3U Vent or fan panel - rack is delivered with blank panels pre-installed covering the top