APC Smart-UPS X 120V External Battery Pack, 4U RM/Tower, Lead Acid Battery

Hot-swappable batteries Ensures clean, uninterrupted power to protected equipment while batteries are being replaced Rack/Tower convertible Protects the initial investment in the UPS when migrating from tower to rack-mount environment. Scalable runtime Allows additional run time to be quickly added as needed. User-replaceable batteries Increases availability by allowing a trained user to perform upgrades and replacements of the batteries reducing Mean Time to Repair (MTTR)