Symbol 6343 from IEC 60417 - Title/Meaning: Maximum altitude 
Function/description: [To indicate that the appliance is intended to be usable up to the maximum altitude 3 000 m. The letter symbols ""3 000"" may be replaced by those for a different numerical value (in metres) in agreement with actual applications. The recommended value should be either 2 000, 3 000, 4 000, or 5 000 (metres).]
Own work using: iso.org/obp/graphics/grs/5bf8cf7b-d2b4-4a51-81d4-d5c21264d070 200.png
Vectorization:  Mrmw