7#: inner diameter 17.3mm
7.5#: inner diameter 17.8mm
8#: inner diameter 18.2mm
8.5#: inner diameter 18.6mm
9#: inner diameter 19mm
9.5#: inner diameter 19.4mm
10#: inner diameter 19.8mm
10.5#: inner diameter 20.2mm
11#: inner diameter 20.6mm
11.5#: inner diameter 21mm
12#: inner diameter 21.4mm