Foam Pencils have special lead and are designed to draw on foam without causing damage. The colors will not bleed through paint or other coverings. Each package contains two red and two black pencils. The SubTerrain Lightweight Layout System does not require any experience to build a layout. There are no complicated calculations to make, no expensive power tools to buy and no dusty mess to clean up. This revolutionary system consists of sturdy, durable and lightweight foam components that take the guesswork out of designing and building a layout, and Tools and Adhesives are specifically designed to work with the System. Read an excerpt on SubTerrain from The Complete Guide to Model Scenery to learn more. Watch the SubTerrain demonstration video here.