Ashlar Tandem is a wall system that creates a unique modular look and can be used in many ways: retaining walls, pillars, double-sided walls, benches and steps. This revolutionary wall replicates the look of natural stone. This product is available in the following sizes - 7 x 13 3/16 x 2 5/8 | 7 x 15 13/16 x 2 5/8 | 7 x 18 7/16 x 2 5/8.