Cliff k19 series knobs for 6mm splined shafts cliff fcr7172 the cliff k19b 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 fcr7172 k19b knob 13mm diameter black