7 diameter 17.3 mm (0.68 inch)perimeter 54.4 mm8 diameter 18.1 mm(0.71 inch) perimeter 57 mm9 diameter 18.9 mm (0.74 inch)perimeter 59.5 mm10 diameter 19.8 mm(0.78 inch)perimeter 62.1 mm11 diameter 20.6 mm (0.81 inch)perimeter 64.6 mm12 diameter 21.4 mm (0.84 inch)perimeter 67.2 mm13 diameter 22.3 mm (0.88 inch)perimeter 70 mm* Please check the Size Chart photograph carefully and see the detail measurements for an accurate fit.