This is a set of two black plastic potentiometer knobs in the classic top hat style, with fluted sides and a round aluminum top piece. These knobs include a set screw and are intended for use on shafts that have a flattened area for best results. You may need to file a flat area into a knurled shaft (such as our audio pots) to get the tightest/firmest grip. These knobs will fit either a .25 or a 6mm shaft. These knobs are a little larger than the other black plastic top hat knobs we sell, being 1.0 in diameter and 0.56 high. These knobs look great on cigar box guitars, amps, and other homemade instrument creations!