'Pennsy' O-Scale FlexiWall - Flexible polyurethane foam may be bent to 8" dia. radius curve Concave or Convex. Gray primer base finish. Featuring interlocking dovetail edges. Outside dimensions: Approximately 14" W x 7" H x 1/2" thick. When pieces are interlocked forms a 15" sectional wall. Matches complete 'Pennsy' Stone System.