These Allparts 3-Way Switch Tips for Telecaster were used by Fender on the "No-caster," Broadcaster® and Telecaster® from 1954. It was also used on many lap steel guitars from the '40s and '50s.
Details:
Many players including Danny Gatton prefer the low profile of this black plastic knob.
The barrel knob for metric switches fits a .047 inch by .138 inch (1.2mm x 3.5mm) lever stem.