Model Number: O4 Silver Plated Inner Diameter: 16.662mm Throat Diameter: 4.646mm Cup Shape: V-Cup Shank: American Purchased about 8 years ago. This is a model with a quite thin rim. I bought it for around 18,000 yen and used it for half a year. The shank was modified at that time, so please be aware of this. No claims and no returns accepted.