Allparts SK-0040-023 Switch Tips For USA Toggle - Black
$3.99
From Allparts:
TOGGLE SWITCH KNOB
Plastic knob thread that works on a 3-way pickup selector toggle switch. Fits any USA made switch, and it can also match the old one that you lost.
Specifications:
• Screw on easy
• Overall Dims 9/16" x 1/4" at .5 grams