Tone Ninja Genuine Ebony Tulip Tuner Buttons (6) fits most Schaller tuners | Reverb
Amazon.com: BQLZR 6pcs Guitar Tuner Buttons Full Size Buttons Alloy Machine Heads,Hole Diameter 4mm,Metal Guitar Tuning Buttons For Acoustic Guitar Line Up and Push on to Install : Musical Instruments
Waverly Guitar Tuners with Ebony Knobs for Solid Pegheads - StewMac
Rubner EL Sonido Vintage / Ebony Tuning Machines — RubnerTuners.com