Mentor 4132.063 Knob Cap For Plastic Turning Knob Collet Fixing - ...

Mentor Caps for Plastic Turning Knobs - Mentor 4132.063, A Mentor cap compatible with 20mm knobs. Mentor 4132.063 Knob Cap For Plastic Turning Knob Collet Fixing - Black - 21.5mm

Price: 0.17 from Rapid Online Rapid Electronics Ltd.