If happen to come to own one of these bad boys from the late 60’s early 70’s you are going to need this owners manual. The original owners of these models rarely have this on-hand. If you are in the market, beware of any models from the 13 line since that model had a well-known faulty oxygen tank that is likely to scrub any potential trips to the Lunar surface you may have planned. Get it from Haynes online.