Cliff FC1610 K1C Knob Black - 1/4" 6.35mm Screw Fix

Cliff K1C Black Control Knobs - Cliff FC1610, A classically-styled, low-cost black plastic screw fixing knob to suit ¼in. shafts. Cliff FC1610 K1C Knob Black - 1/4" 6.35mm Screw Fix

Price: 1.85 from Rapid Online Rapid Electronics Ltd.