Hoppe's No. 9 Conversion Adapter, .17-.22 Caliber Quality materials used 100 percent designed and tested For the toughest situations and environments Interchangeability with non-standard size threads This is a great, easy to Use adaptor Hoppe's No. 9 Conversion Adapter permits interchangeability with non-standard size threads Intended for use with .17-.22 caliber This is a great, easy to use adaptor