Symbol 2164 from ISO 7000 - Title/Meaning: Variability, for rotating movement, variability in steps Function/description: To identify the control by means of which a quantity is controlled stepwise.
Additional information: 
Motion of the operating device towards the wide end of the wedge results in an increase in quantity or rate. Motion of the operating device towards the point of the wedge results in a decrease in quantity or rate.
Own work using: iso.org/obp/graphics/grs/e1a30b95-443f-4892-b7f5-91cca5d02e12 200.png
Vectorization:  Mrmw