Symbol 0503 from ISO 7000 - Title/Meaning: Symmetrical course 
Function/description: To indicate the setting of a symmetric run (for example, operating controls switching the symmetric run of a fabric web on or off).
Own work using: iso.org/obp/graphics/grs/31e2ffa9-62e4-402e-817f-823f98405ced 200.png
Vectorization:  Mrmw