Tilz M1 This is a Tilz mouthpiece that is not sold very often recently. The specifications are as follows: I used it thinking it had European helper-like specifications (in my opinion). The shank is Euro, so it will be relatively shallow. It's an old item, and I also purchased it used, so I'm selling it at a low price. Mouthpiece Cup Depth: Deep Mouthpiece Bore: 8.3 mm Mouthpiece Cup Diameter: 33.00 mm