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, I will send them by regular mail. Please note that there is no compensation. Thank you for your consideration. [Attention] I will refuse to sell to those who cannot rate immediately after receiving the item. I may respond with a rating depending on the situation. However, this does not apply if you have explained the situation in advance. Thank you.