The AP9625 was created in order to provide a means to mount certain Smart-UPS models, all Symmetra RM models and the 208/120V step-down transformers in standard 2-post racks. 2-Post racks are common in wiring closets and the need to provide back-up power in these environments has increased with the application of VoIP (voice over internet protocol). This kit replaces the older SYOPT6, SYOPT7 and SYOPT8 kits.