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