Well, 5/8 inch thick, 100 pages is certainly not a full fledged service manual, but sure looks like it covers most of the items the average owner would need. Might want to take a look at the description. I doubt that a bus driver is going to change injectors, injection pumps, adjust valves, etc. Anyhow, I got one for my growing collection. I have found with the Cummins manuals, if you got 6, you often get 6 different ideas of how to fix em. My favorite so far is the Service Manual on a CD.