taiss / 10pcs silver tone top rotary knobs for 6.4mm / 0.25" dia. shaft 3590s potentiometer, switch knob top diameter: 23mm black a03-6.4mm taiss this rotary knob is made of plastic material, 6.4mm metal hole, 360 degree turning, a built in screw make it can be adjustable.decorate your furniture or various appliances, musical instruments. - a good accessory to replace your broken knobs. - high quality and 100% brand new, testing is fine.