Summary: This unit used the main ATX power connector to supply its own power for operation, so it doesn't need batteries. Operations of basic power supply checkup is pretty simple, but you may need to read the (brief!) user manual to figure out the abbreviations for what's it's checking.
Summary: When I open the box the transparent plastic was cracked. I believe, it was a return. But, it works. When I tested my power supply the display was placed red, I was very afraid, but I noted that the 24pin connector was not fitted well. I connected in the right way and finally works.
Summary: If you are in IT or just working at home on computer projects, this is a must have in trouble shooting power issues which could be the cause of many things with you system. It is easy and simple and works pretty good.