Brian,
I read the reviews of that product. No direct experience, but 1 of three reviews says it worked for 1 minute before breaking. He probably tried charging something which required more than 12V.
that said:
What are you trying to power with this? If it is microphones-NO- if it is almost anything else, that may be the deciding factor. as in anything without a huge surge potential (ie printers, vacuums, de-humidifiers surge heavily on start up) should be able to be powered by this thing.
Finally, if it is microphones, kindms gave me this power transformer type box with XLR in/outs which I think steps down, but I will check it tonight.