30' Single Track Through Girder Bridge Kit - Features: Part of the Cornerstone Engineered Bridge System, Fits Steam, Diesel & Modern Eras, Use Over Highways, Waterways, & Other Railroads, Build with Open or Ballasted Deck, Perfect as Approach Spans for Bigger Cornerstone & Other Bridge Kits, Molded in Dark Gray Plastic. - Dimensions: 4 1/8" L x 2 3/8" W x 1"H. - Walthers Cornerstone Item # 933-4500.