Size: 40 is 10
Total length: 43.5
Measurement taken in inches, flat, at the smallest: 17 (x2 for the circumference)
Measurement taken: in inches, flat, at largest: 19 (x2 for circumference)
Size: 42 is 12
Total length: 45.75
Measurement taken in inches, flat, at the smallest: 18 (x2 for the circumference)
Measurement taken: in inches, flat, at largest: 20 (x2 for circumference)