?Size Reference
????? Code ????????? inner length?
21???????????????? 13cm
?? 22 ??????????????? 13.5cm
23 ??????????????? 14cm
?? 24 ??????????????? 14.5cm
25 ??????????????? 15cm
26 ??????????????? 16cm
?? 27 ??????????????? 16.5cm
28 ??????????????? 17cm
?? 29 ??????????????? 17.5cm
30 ??????????????? 18cm