Symbol 5124A from IEC 60417 - Title/Meaning: Slow run; slow speed Function/description: To identify the control or the indicator to operate at a slower speed than the normal speed and in the direction indicated by the triangle.
Additional information: 
In the orientation shown, the graphical symbol means ""slow run, forward.” If it shown reversed, the graphical symbol means ""slow run, backward.”
On audio video equipment, the symbol 5124B is the preferred alternative and should be used in combination with any of the symbols 5107B, 5108B, 5111B and 5110B
Published in: Supplement K, 1991;Supplement J, 1990;Supplement F, 1982
Own work using: iso.org/obp/graphics/grs/5376287e-5805-46f9-b175-9b194d7866ed 200.png
Vectorization:  Mrmw