＜p＞These corks are designed for Irish/simple system flutes and do not include the center hole found in corks for silver/Boehm flutes. They are available in 18mm, 19mm, and 20mm diameters. (33mm long)＜/p＞ ＜p＞The internal headjoint diameter of most flutes is slightly less than 19mm. To fit, you can sand down the 19mm cork or adjust the 18mm cork using paraffin wax or a few wraps of Teflon/plumber's tape.＜/p＞ ＜p＞＜br＞＜/p＞