Fine textured black concentric knob. SPECIFICATIONSOverall Height: 7/8"Base Diameter: 1"Ideal Shaft Fit: Bottom = 17/64" (6.75mm) | Top = 3/16" (4.75mm)Fit Type: *Set Screw Tech's notes: "These will ONLY fit on the CTS stacked concentric pots we carry."