Have used this for about a year and a half...power back up is fine, though seems to set off my computers alarm more often than not. My real issue has to do with the crappy surge protection. Storm hit last night and my Motorola Modem, Apple Airport Extreme both got smoked and apparently have lost at least 2 ports on the back of my iMac. Use with Caution.. I'm gonna be out over $1000 thanks to their lack of quality.