Works exactly as advertised. I'm using it to support my internet modem & router as well as a Synology NAS. The latter supports shutdown control from compatible UPS units, and this one works well. No shutdowns yet (power is quite reliable here) but there have been some "bumps" that caused power-status-change emails from the NAS, and that's a good start (I didn't notice any of the events). The batteries are not listed as "user replaceable" but the batteries are easily accessible (undo two screws under the bottom edge of the front panel) and appear to be standard 12V units similar to those commonly used in this kind of application.