The C-pillar is the rear section frame of the car that connects to the roof. Unlike
a rear strut bar that is usually hidden under the car or within its sub-frame,
the C-pillar bar installs in the interior holding the rear suspension. Because
suspensions on most cars are softer and geared more towards comfort, they tend
sway slightly. However, with the C-pillar bar, you can help in reducing the
rolling effect during turns. C-pillar bars can sometimes be used to anchor a 4-5
point seat belt harness depending on the setup.