Water key corks for trumpets. Set of 4. I think they can also be used for cornets, trombones, flugelhorns, etc. Outer diameter: 10mm Thickness: 4mm To offer them at a low price, they will be sent by regular mail, so there is no compensation. Please understand. Thank you for your consideration. [Note] We do not accept purchases from those who cannot rate immediately after receiving the item. We may respond with a rating in some cases. However, this does not apply if you have explained in advance. Thank you.