Model Number: 2W Inner Gold MacWilliams Model Inner Diameter: 17.7mm Throat Diameter: 4.2mm Cup Shape: U Cup, Tilz MF marking Shank: American This is a larger size than the MacWilliams 2. Personally, I found the gold plating on the inner cup and rim to be comfortable on the mouth, and I felt slightly more resistance than with silver plating. *There is no box, so it will be wrapped in bubble wrap for shipping.