The Bruno Tilz Adapter Trombone-Bass Trombone that I have got does not work. Its interior diameter is too large: the tenor trombone (small shank) mouthpiece goes all the way in and still remains loose. I have tried with multiple small shank trombone mouthpieces: Bach, Warburton, Marcinkiewicz... none of them fits in the adapter! They all remain loose. So, the adapter I got was totally useless. The question is whether all Bruno Tilz Adapter Trombone-Bass Trombone are too big, or is mine had a a fabrication error.
Whatever the reason, it is regretful.