Inner length:
21 yards: 13cm 22 yards: 13.5 cm
23 yards: 14.1 cm 24 yards: 14.7 cm
25 yards: 15.3cm 26 yards: 15.9 cm
27 yards: 16.5 cm 28 yards: 17.3 cm
29 yards: 18cm 30 yards: 18.5cm
31 yards: 19 cm 32 yards: 19.5 cm
33 yards: 20.1cm 34 yards: 20.7 cm
