Image Item No. Description By  3659  Arch 1 x 4 Catalog: Parts: Arch 2  15254  Arch 1 x 6 x 2 - Medium Thick Top without Reinforced Underside Catalog: Parts: Arch 1  12939  Arch 1 x 6 x 2 - Thin Top without Reinforced Underside Catalog: Parts: Arch 9  6184  Arch 1 x 12 x 5 Curved Top Catalog: Parts: Arch 8