- Available Types: a. 1/6 Length: 20 - 38 mm Outer arc: 32 - 43 mm Thickness 9-11 to 18-22 mm b. 1/8 Length: 20 - 38 mm Outer arc: 20 - 38 mm Thickness 9-11 to 18-22 mm c. 1/12 Length: 20 - 38 mm Outer arc: 10 - 30 mm Thickness 9-11 to 18-22 mm d. 1/16 Length: 20 - 40 mm Outer arc: 10 - 25 mm Thickness 9-11 to 18-22 mm