roll bar

/R OW1 L B AA0 R/
noun
  1. 1

    A strong U-shaped bar fastened to the frame of a vehicle, such as an off-road vehicle or a race car to protect the driver and passengers from being crushed in the event that the vehicle rolls over.

  2. 2

    An anti-roll bar.

Source: https://en.wiktionary.org/wiki/roll%20bar