Black Iron Grille - Measures Inner Diameter: 12 Inches (305 mm) by 2 Inches (51 mm). Outer Diameter: 14 Inches (356 mm) by 3 1/2 Inches (89 mm). Drop In Style Standard. These are individually cast in solid iron - durable and heavy for decades of service. The cast iron is approximately 0.2 inches thick (5 mm) and will easily hold over 400 pounds.