| XS | S | M | L | XL | XXL | |
| a | 18 3/4 inches 47.5cm |
19 3/4 inches 50cm |
20 3/4 inches 52.5cm |
21 3/4 inches 55.5cm |
23 1/4 inches 59cm |
24 1/4 inches 62cm |
| b | 26 inches 66cm |
26 3/4 inches 68cm |
28 inches 71cm |
28 3/4 inches 73cm |
29 1/2 inches 75cm |
30 1/4 inches 77cm |
XS
a – 18 3/4 inches / 47.5cm
b – 26 inches / 66cm
S
a – 19 3/4 inches / 50cm
b – 26 3/4 inches / 68cm
M
a – 20 3/4 inches / 52.5cm
b – 28 inches / 71cm
L
a – 21 3/4 inches / 55.5cm
b – 28 3/4 inches / 73cm
XL
a – 23 1/4 inches / 59cm
b – 29 1/2 inches / 75cm
XXL
a – 24 1/4 inches / 62cm
b – 30 1/4 inches / 77cm