When you buy a training manual or video from ebay, you should talk to your instructor or dive center first to make sure that the version is the same as the one that you will need for class.  I see a number of agency training materials that are far out of date and will not work for a dive training course.   I am a PADI instructor and students come to me all the time that have bought a manual off of ebay and when they show up, the manual is out of date or missing components.  Your best bet is to buy from a store or instructor with training agency affiliation (eg. PADI, NAUI, SSI, etc.)and  to check with your instructor or dive center first!  It never hurts to ask a seller a question about what you are buying.  If they don't know, chances are you should not be buying training materials from them.  Get the version of the manual, date of original purchase/publication from the seller.  If the book is more than one year old or has been used, chances are that it is out of date and will not work for your class, most agencies require you to purchase a NEW manual to go with your classes so a used one should be avoided at all costs.  It is no fun to have to buy the stuff twice. With that said if you are buying the manual or training materials as a novelty or collectors item then there is no issue with any manual out there. I have a few old dive training manuals from the 60's, 70's, and 80's that I bought just to see how the sport of diving and the training of new divers has changed over the years before I got into diving. Thanks for reading and safe, happy diving to all of you! See you underwater, Howard Cunningham PADI OWSI #193865