GP KN55CH Concentric Knobs Set Chrome - Metric
Concentric Stacked Knob set, with set screws, Chrome, fits Import Stacked Pots
Top knob is 7/16 inch tall x 9/16 inch wide with .236 inch hole diameter.
Bottom knob is 15/32 inch tall x 3/4 inch wide with 5/16 inch diameter hole.
Top knob sets into bottom knob for a total combined height of 27/32 inch.