Woodland Scenics ST1409 4 Inch Risers.

Risers are generally used with incline/decline starters to create varying grades on your layout. Risers are easily flexed to form curves and work on plywood or foam bases. To install, pin in place with Foam Nails and attach with Foam Tack Glue™ or Low Temp Foam Glue Gun and Glue Sticks.

These risers are 24 inches (609mm) (length) by 2 1/2 inches(635mm) (width) by 4 inches (100mm) (height). There are 2 i the package.