The Schilke D5.2 mouthpiece is for those who appreciate a bit of room for the chops and a depth that helps provide the potential to make a clear and resonant symphonic sound. The extra room can help with flexibility in singing/playing up and down the range. The rim on the Symphony range has been made to feel more comfortable than the standard range. The Schilke factor in all of this makes for a sound thats really quite resonant, with overtones present and alive compared to other mouthpiece makes who sound well but do less to help create the same degree of resonance. The clarity of articulation that can be achieved on a Schilke is also highly notable. I have used this mouthpiece on the Elkhart Conn 88h and Bach 42 trombones across a diverse range of orchestral repertoire and the response is very pleasing. I wouldn't hestitate to recommend any models of the Symphony range. The D5.1 too is very good and makes a lovely rich deep noise, or whatever the noise you want to make!