O-rings for trumpet, cornet, and flugelhorn tuning slides. Fits at least YAMAHA. Made of nitrile rubber. Set of 10. Diameter: 12mm Inner diameter: 10mm Thickness: 1mm Although only 4 are used for one trumpet, we've included 2 extra in case any break or get 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, we will ship via regular mail. Please note that there is no compensation for loss or damage. Thank you for your consideration. [Important] We will not accept purchases from those who cannot provide an evaluation immediately after receiving the item. We may respond with an evaluation accordingly. However, this does not apply if you have explained the situation in advance. Thank you for your understanding.