This is a set of 8 black plastic ribbed potentiometer knobs, which have a white line marker on top. They are press-fit knobs intended for a knurled 6mm shaft. Please refer to the size diagram to the right for size reference. These knobs are manufactured by Eagle Plastic Devices. Please note that the coins and cigar box detail in the photo are for reference only; this product offer includes only eight of the pictured knobs.