I purchased this for a cornet, but it didn't fit, so I'm selling it since I bought a different one. It's practically unused, as I only used it for a few minutes to test it out. Plating: Silver plated Size: 2C Diameter: 16.5mm Backbore: 10 Cup Depth: M (Medium) Regarding the cup depth, it felt a little deeper than medium. I will clean and disinfect it with alcohol before shipping. Also, there is some damage to the box from when it was opened (see photo 4). Please feel free to ask if you have any questions.