Basically a mix of tables for quick reference for DMs and a few sheets where the DM can keep information about the party such as their class, hit points, armor class and so forth, which are useful to determine combat results.

This comes in the sequence of a series of accessories for AD&D, some more useful than others. This one is pretty superfluous as all the info is either in the oficial DM Screen or in the DMG and you could just note down the player info in a piece of paper (or even trust your players to keep track of that, I know, crazy), but it’s still a nice bit of convenience. Worth it for the cool Erol Otus cover!