It is for rubber. Basically, it can be used with mouthpieces (Yamaha and Selmer rubber types) that fit Yamaha genuine ligatures. Please note that it may not be possible to use it depending on the mouthpiece model, manufacturing date, or combination with the reed.The cap is compatible with Rondino. Made of aluminium. Made of extremely rigid material (different from 1 yen coins and aluminum cans). No need to worry if you accidentally drop it.
