The problem with these UPS devices is they beep! When running off the battery, they beep regularly -- at least all the ones I've seen do.
Also, this is a good price and you may be getting what you pay for! I'm not all that happy with APC. I had an APC UPS and had problems. In less than a year, the batteries quit charging. I contacted them and they sent new batteries. The new ones were slightly different than the old ones and it was quite a struggle to get them connected and back in the case. Then barely after the warranty expired, it decided to not charge the batteries!
I got rid of it and bought a different brand (Global Power, I think).
The APC one had to be plugged in AND turned on continuously to keep the batteries charged. The new one (now long outside warranty) keeps the batteries charged even if it is powered off. That is much better and allows it to be used as needed.
It's so smooth that if there is a short outage, you see NO flicker or problem on the computer -- just the lights in the room go out (and any fan that might be turned on).
I personally would not waste even $13 on APC after my personal experiences.