This knob is designed to work with the stock potentiometer, and is friction-fit (no set screw). The shaft will need to be cut down to approximately 1 cm in length in order to fit these knobs. NB: Due to slight variations in printing techniques, some materials may need slight filing and/or shimming (e.g. with tape) in order have an ideal fit onto the encoder shaft. I have had several materials printed, and some are slightly too tight, and some are slightly loose.
Material choice is very much up to the end user. The plastic knobs are very lightweight (and inexpensive), while the metal ones are heavy and give an extremely luxurious feel. For the person who truly wants a gold (and not just gold-plated) radio, precious metals are also available. It is worth taking the time to read about the material choices before making a selection.
Please note: This is only the volume knob! If you'd like a matching encoder knob,order it here.