I'm not certain exactly when these products were released, but given that the first one was included with the original Basic Set it has to be before this point. I've lumped all three together at the end of what I consider the OD&D era, but that doesn't necessarily mean that this is when they came out.
The purpose of these products is to make it easier for a DM to run dungeons on the fly. It gives a random encounter chart for dungeon levels 1 to 9, giving each dungeon level 100 different results. Likewise, there are charts for determining random treasures. This is much larger variety of results compared to the previous random encounter charts used, and for the first time it includes a range for the number of monsters encountered. I've never found a use for these products in the past, but it looks to me as though they would make for a much more varied dungeon campaign, if your DM happens to be running the usual methods for random encounters. I'll run my game with these charts for a while before the OD&D era ends. Although I do wonder what this would do to the monsters introduced in Supplements I to III. A quick glance shows that there are a few Demons here, so it looks pretty safe.
There's a brief introduction that gives some advice on stocking the dungeon, but it's all pretty basic stuff. The only thing of note is an example that fills a number of rooms. I'll be using that example to fill out the sample dungeon from Volume 3 of the OD&D boxed set.
Alas, there's not actually a lot else to be said for this product. It is, after all, just a collection of charts and not much else. So forgive me for the short entry.
And that's the end of the OD&D era. I'm beginning the AD&D era with the original Holmes edition of the D&D Basic Set, but I won't be getting to that for a while. As I noted on the blog earlier, I'm taking some time off from the regular schedule to piece a lot of this campaign together. I'll post all of that material, so there'll still be regular updates, but I'm not yet certain what form they're going to take, or how often the updates will come. But rest assured, I'm not abandoning this thing after so much work, so if you don't see me around here for a while, that's okay. I'll be back when you least expect it.