The BP48V48RT4U 4U external battery pack offers extended battery runtime when used in conjunction with expandable 48V rack-mount and tower UPS systems. 4U reduced-depth configuration with included 2-post mounting accessories is ideal for use with compact rack-mount models SMART2200CRMXL and SMART3000CRMXL. Includes heavy-gauge cabling with high-current DC connector for safe, simple installation. Included daisy-chain connector enables the connection of additional compatible 48V external battery packs to the host UPS. Included mounting accessories support 4U balanced two-point center-mounting rack-mount installation in 2-post racks. Options for 4-post mounting available.Compatible with these UPS Systems: SMART2200CRMXL, SMART3000CRMXL and other UPS systems that specify the use of this battery pack. (Note: BP48V48RT4U, SMART2200CRMXL and SMART3000CRMXL include hardware for 2-post rack-mount installation. Most other rack-mount UPS systems and battery packs include hardware for 4-post rack-mount installation.)