These knobs are all ¼” horizontal grain Bubinga (African Rosewood) glued to ¾” vertical grain Brazilian Cherry. The end grain of Brazilian Cherry (top of knobs) looks like brown pinstripe. The pale red Bubinga has iridescence. All have #5-40 x 3/16” set screws. Finished with Kiwi neutral shoe polish over layers of Minwax Polycrylic water-based clear acrylic. Tulsa blues guitar man John E. Landis graciously accepted their presentation to him.