This Box Contains One HO Scale Double Track Concrete Tunnel Portal for Your Model Railroad Layout from Woodland Scenics. Tunnel portals are the stone, concrete, or timber facings built at the entrances to tunnels. They hold back rocks and dirt from tunnel entrances and often are used in combination with retaining walls. FEATURES: This concrete tunnel portal is cast in high-density Hydrocal. Wide enough for two HO scale track to run through. This white cast is authentically detailed in appearance and texture. You can use this portal alone or in combination with retaining walls. Create ultimate scenic realism simply and economically. Ready for staining or painting right from the box. Easy to follow instructions for installation of portals. INCLUDES: One HO Scale Double Track Concrete Tunnel Portal REQUIRES: Adhere Portal to Layout Lightweight Hydrocal, Flex Paste or White Glue Hobby Knife, Sandpaper or File Earth Color Liquid Pigments SPECS: Scale: HO 1:87 Outside: 7 3/8" w x 4 7/8" h (18.7 cm x 12.3 cm) Inside: 4 5/8" w x 3 13/16" h (11.7 cm x 9.68 cm) COMMENTS: Hydrocal is a product of U.S. Gypsum. For further information on installing tunnel portals, as well as complete instructions for creating landscape and terrain, read "The Scenery Manual" (WOOU1507).