Smart-UPS protects your data by supplying network-grade battery backup when power fails. With PowerChute plus software the uninterruptible power supply (UPS) will safely store data and shut down your network operating system before the battery is fully discharged, whether you're there or not. SmartSlot internal accessory slot allows you to install optional accessories to enhance the performance of your UPS. APC Smart-UPS is the perfect UPS for fileservers, minicomputers, UNIX CPU s, internet hubs, telecommunications systems and other mission-critical applications.??Smart-UPS XL models (Smart-UPS models with XL extensions in their names and part numbers) allow for expanding runtime by simply plugging in additional battery packs.