Thank you for viewing. This is an ULTIMATE BRASS 1782+. I imported it from America this winter, but the inner diameter is 18.1mm, which is too large for me, so I am selling it. Inner diameter: 18.1mm Throat: 4.25mm It's a deep mouthpiece, and it's probably an American shank, but it worked without wobbling on my Alexander 103. It seems it was originally a mouthpiece for trial use, so there are some scratches on the shank, but there were no problems with its use.