bb/f tenor transposition playing trombone flat b to f white copper pull tube trombone marching band

hello my friend i am very glad that you can visit my shop i am chinese i have a very professional factory in china it is very good many of my teachers in china are very good friends because they can give me a lot of professional and good advice which is very helpful for my business at the same time i also hope that i can get advice from foreign friends.syi