Use Retaining Walls alone, installed adjacent to each other to create straight or curved walls or use with Tunnel Portals. Cut to varying heights to create stepped, winged walls. Color with Earth Colors Liquid Pigments. 2 11/16" h x 1 5/16" w, 105' scale length (6.82 cm x 3.33 cm, 32 m scale length) About Terrain Structures Tunnel Portals, Retaining Walls, Culverts, and Roads reinforce natural terrain contours and add functionality, realism and interest to your layout. WARNING: CHOKING HAZARD - SMALL PARTS! NOT INTENDED FOR CHILDREN UNDER 3.