Middle Atlantic SPN-R4-4530 This SPN-R4-4530 Keylocked Side Panels for R4CN-4530B from Middle Atlantic is a pair of side panels designed for use with the R4CN-4530B four-post open-frame rack. Use side panels to protect your valuable equipment from dust and other foreign debris. The side panels are constructed of steel and feature a black finish that matches the rack frame. A keylock on each panel provides an additional level of security for your equipment.