O-rings for trumpet, cornet, and flugelhorn tuning slides. Fits at least YAMAHA. Made of nitrile rubber. Set of 5. Diameter: 12mm Inner diameter: 10mm Thickness: 1mm Although only 4 are used for one trumpet, we've included an extra one in case one breaks or gets lost. These are thinner than Yamaha's genuine ones, so the impact on pitch and resistance should be lower. The photo shows a Yamaha trumpet with these O-rings installed. To offer them at a low price, they will be shipped via regular mail, so there is no compensation for loss or damage. Please understand. [Important] We do not accept purchases from those who cannot rate the product immediately after receiving it. We may respond with a rating accordingly. However, this does not apply if you have explained the situation in advance. Thank you for your understanding.