This slim and modern potentiometer is small and compact, yet looks good and has a nice feel. Adafruit hand selected the best knobs for your project in different sizes and varieties. This one is the Slim Metal Knob 10mm diameter x 10mm Tall (T18 Splines).
It's a brushed aluminum knob with a shiny black (anodized?) coating. It kind of looks like the type of knob you'd find in a very fancy, modern kitchen. There's a silver mark on the black finish so you can know where you are and figure out where you're going. It's a good knob if you're looking for something basic and subtle and it's super tiny and subdued. Adafruit also have a taller version in the same style.