TRIPP LITE BP48V27-2US 48VDC External Battery Pack Select AVR Online UPS Rack Tower 2U Extends the runtime of compatible 48V Tripp Lite UPS Systems Included daisy chain connector supports the addition of multiple compatible external battery packs Supports 2U rack mount installation; 4 post installation accessories included Options for 2 post rack mount and wall mount installation available 2-year limited warranty