All sizes given are subject to manufacturing tolerances (+/- 2%). Men's a. b. Extra Small 70cm 48cm Small 72cm 51cm Medium 74cm 54cm Large 76cm 57cm Extra Large 78cm 60cm XXL 80cm 63cm 3XL 82cm 66cm 4XL 84cm 69cm 5XL 86cm 72cm Kids' Sizea.b.4 Years48cm36cm6 Years52cm38cm8 Years56cm40cm10 Years60cm42cm12 Years64cm44cm14 Years68cm46cm