Symbol 2104 from ISO 7000 - Title/Meaning: Moving machine alarm; rearward moving vehicle alarm 
Function/description: To identify the control that sounds an alarm when the machine is moving rearward. To indicate the operational status of the rearward-moving vehicle alarm.
Own work using: iso.org/obp/graphics/grs/82105adc-d585-4c17-919c-b700017d7840 200.png
Vectorization:  Mrmw