Made of acrylic, the ARCH Platform consists of a top plate that rests over a number of ARCHs placed on a bottom plate. The regular size platform measures 18x14x1 inches. The medium platform is 20x16x1. The large platform is 22x18x1 and the jumbo platform is 24x20x1. ARCH platforms do not include the ARCHs, which can be purchased separately to support the appropriate component weight loads.