Material: Titanium steel,Color: as the picture shows,Size: width 8mm\uff0c,         inner diameter 16mm /American size 6,,         inner diameter 17mm /American size 7,,         inner diameter 18mm /American size 8,,         inner diameter 19mm /American size 9,,         inner diameter 20mm /American size 10,,         inner diameter 21mm /American size 11.,Package Includes: 1pc