Cliff k19 series knobs for 6mm splined shafts cliff fcr7171 the cliff k19a knob fits controls with 6mm splined shafts to give a neat finish the knob has been designed such that the lower collar of the knob sits through the front panel hiding the shaft of the controlthe knob is black in colour with a white 15mm marker dot cliff fcr7171 k19a knob 15mm diameter black