Brand BBPG-G Booster for trombone mouthpieces, gold finish, the booster has a refined holding system that prevents tracks but can still be fixed firmly on the mouthpiece, plastic mouthpieces therefore have a similar weight to metal mouthpieces while retaining the more comfortable feel on the lips, can also be assembled on all common metal mouthpieces, the weight of the mouthpiece reduces vibrations, the tone is more centred and notes can be hit precisely, Set incl. 3 threads for S, M and L shank