York Master model trombone and original case I know absolutely NOTHING!!!!  About instruments trombones or there functions lol . Other than asking me for some more photos I don't know what to tell you I am selling this thing as is I did see a k id put it together at an auction and blow in it and it did make a trombone sound lol it is not  in perfect condition does have 2 dents that I could see but again other then that I don't no what to tell you info wise. Happy bidding