The word "trundle" means small wheel and that is what the lower bed has -- small wheels for rolling under the bed frame. Project is ideal for use in any bedroom as a unique space saver. The joinery is accomplished with keyed / pegged tenons, as was used by early craftsmen. The plans detail twin size only, but the intermediate could easily expand the project. This is a blueprint style plan which is heralded by beginners and experts alike as being a pleasure to work from because all parts, joinery, curved workpieces are printed in actual size, therefore you can measure and trace straight from the drawing if necessary. A bill of materials doubles as an exact cutting list, there is a detailed exploded diagram, and all hardware requirements are provided. The exploded diagram so detailed that project specific assembly instructions are not provided. A special booklet entitled Guide to Building Wood Furniture is included with each Furniture Designs, Inc. plan and includes many tips explaining the "component theory" of woodworking.Dimension: 39 1/2"H X 42"W X 83 1/8"L