Hello, l just joined. I've been playing euphonium for about 5 years now. Since I'll be playing outside in the cold a lot, I was looking to buy a plastic (Kelly) mouthpiece; however, I'm not sure exactly what moutpiece to buy. I have a standard yamaha YEP-221 euphonium. I honestly have no idea about what kind of bore or cup or anything to get. Can anyone help me out here?