From the back of the book:
"Build Your Own Crypts and Catacombs
Your tabletop never looked better! With Dungeons & Dragons Miniatures and this pack of customizable grids, you can add a new dimension to your D&D adventures.
Easy to set up and infinitely expandable, this pack allows you to create the dungeons and adventures you want to play. Pick up additional packs to create larger, more elaborate dungeons!
This pack contains six durable, fully illustrated dungeon grids, featuring rooms, corridors, and passages of various sizes, plus doors, walls, and other terrain elements that you can use to make great D&D encounters that enhance your roleplaying game experience.