Andy Kunz wrote:

> They mean with 500 watts audio output you'll be able to hear it from 2
> miles away.

  I think they may mean 500 W PMPO, which is a fancy way of saying 10 W
RMS.  Of course, RMS watts are not meaningful either (FAQ), just a way
of saying "10 watts actual".

  An alternate, but very improbable for the price, interpretation would
be that it comes with, or is accessorised by, a petrol generator set.
--
  Cheers,
        Paul B.