Not sure what you exactly plan to use it for but if your just looking for a cheap co2 to mess around with then this is your best bet. Safety glasses ARE required.
I'm looking to build my own laser engraver/cutter. There are some great plans on a site called buildlog.net but they don't go into detail about the CO2 laser system they're using.
I'm guessing that you're asking about the thread in Buildlog.net? If so, I'm referring to the link "drawings for 2X laser" which has all the drawings and specs on the build in pdf format. You'll see it on the top left side of the home page.
Its more geared to the mechanical components and electronic controls of the machine but there are some references to the laser...just not any specs on the actual laser.