This set is designed to complement the “classic dungeon” Master Maze line, especially the Room (MM-001 & MM-009) and Room and Passages (MM-002) sets. From the publishers website: This most recent supplement to the “classic dungeon” Master Maze line is well worth the wait! This new set contains many highly useful pieces that will allow you to MAXIMIZE the playing area on your table. New “filler” type pieces abound in this set, and they are designed to work around and inside the passage pieces from our classic Room and Passage Set. Areas that were once dead or empty can now be turned into playable rooms, passages, and spaces. Clever designers can now create large setups without unplayable areas within their designs. Such designs could feature realistic castles, inns, temples, or any number of floor plans while still incorporating large 10ft. wide passageways within. In addition to these “filler” type pieces, this set includes classic “passage pieces” with openings (corner and straight) as well as classic corner “room pieces” with openings (one even at a 45% angle) The Set includes freestanding walls to block these openings if desired or to utilize as low walls or other design elements. But mostly, these openings are for our FOUR new narrow doors in the set: Demonic, Runic, Metallic reinforced, and Voice-spell enchanted! Finally, the set includes two straight walls with windows for those designers with abbeys and stone buildings in mind. The window openings are the same size as the windows in the Medieval Building Set, so our shutter inserts will work with these pieces as well. The 42-piece set consists of: X1 Corner Passage with Openings X1 Short Passage with Openings X1 Corner Wall with Openings X2 Corner Wall with Diagonal Opening X2 Narrow Door Metal X1 Narrow Door Mouth X1 Narrow Door Rune X2 Narrow Door Demon X4 Narrow Half Wall X1 2 x 2 Floor w/Notch X2 Half Floor X2 Half Wall X8 2 x 1.5 Floor X6 1.5 x 2 Floor X2 Straight Wall with Window X6 Insert Wall