The knob is not an invention that changed the world, but it can do things that the keys cannot do
As a mechanical structure, the knob is the first to appear on which equipment can not be tested. Maybe it was a telegraph machine from the last century? Or an oscilloscope? It may also be the later radio or TV, which is naturally born on electronic devices like many buttons, and then gradually popularized as a part of the electronic dashboard, and has been used as a controller all the way to this day.
T57-Star knob

Using SUS304 material

Type M: bright finish (mirror)

Type S: Matte finish (sandblasted) has corrosion resistance, under special hygienic, climatic and environmental conditions or in environments where the use of corrosion-resistant materials is mandatory by law

Uses: chemical, food, equipment and testing instruments