Strurbarworks.com

The strut bar (also known as a strut tower brace) is an addition to the suspension of the car, which is placed between strut towers (either front or rear) to give a rigid connection between them.
In addition to the aesthetics, it doesn’t allow the chassis to twist when loaded. By connecting two strut towers with a rigid connection, the entire suspension is reduced to springs and shock absorbers.
You get a much firmer and more accurate car in curves. This part is also needed when driving with more massive wheels every day.
Also, the strut brace protects your car and you during an accident, since it doesn’t allow the car to completely crumble.