Model Number: 27 Silver Plated Inner Diameter: 16.25mm Shank: American Purchased approximately 20 years ago and stored for a long time. The inner diameter is quite small and the rim is thin, so those who usually use 17.00mm or larger will likely find it too small. If 17.00mm or larger feels tight, please consider this as an option. I have performed boiling sterilization and cleaning, but the plating doesn't have much luster. Please understand the specifications and any deterioration (there are no dents, etc.) and purchase with no claims and no returns. There is no box, so I will wrap it in bubble wrap for shipping.