A1) 42 Diameter x H30 A2) 42 Diameter x H30 with 1-24" center extension A3) 42 Diameter x H30 with 2-18" center extensions A4) 42 Diameter x H30 with 8-8" perimeter extensions B1) 48 Diameter x H30 B2) 48 Diameter x H30 with 1-24" center extension B3) 48 Diameter x H30 with 2-18" center extensions B4) 48 Diameter x H30 with 8-8" perimeter extensions C1) 54 Diameter x H30 C2) 54 Diameter x H30 with 1-24" center extension C3) 54 Diameter x H30 with 2-18" center extensions C4) 54 Diameter x H30 with 8-8" perimeter extensions D1) 60 Diameter x H30 D2) 60 Diameter x H30 with 1-24" center extension D3) 60 Diameter x H30 with 2-18" center extensions D4) 60 Diameter x H30 with 8-8" perimeter extensions E1) 72 Diameter x H30 No extensions available on this option