AN IMPORTANT NOTE: This tool and its accessories are designed for use with Woodland Scenics own high-density, nontoxic expanded polystyrene foam. Since many foam products emit a toxic gas when heated, this tool should never be used with ordinary Styrofoam, foam rubber or other foam products. These special nails are designed to hold foam sections, roadbed and other features in place temporarily. Easy to remove, they allow you to refine your track plans and scenery without damage to the surface. Each nail measures 2" long and a package comes with 75 nails.