KN501BA1/8 is a machined aluminum knob from the K Series Alcoswitch product line, designed for rotary control applications. This two-toned knob features a black body with natural top finish and includes a straight knurl pattern with an arrowhead indicator for precise position reference. Key dimensions include a diameter (A) of 0.500 inches (12.7 mm), dimension B of 0.445 inches (11.3 mm), dimension C of 0.374 inches (9.50 mm), and dimension D of 0.445 inches (11.3 mm). The knob is designed for 1/8" shafts with a bore diameter of 0.126 inches (3.20 mm) and uses No. 6-32 set screws for secure mounting. This knob is ideal for control panels, instrumentation, and audio equipment where visual position indication and a professional two-tone appearance are desired.