question about rear height sensors

[Grantkat]

2008 sequoia platinum: I have been trying to adjust the rear height sensors to match up. In the attached picture there is a set screw on the sensor (circled in blue) . if you loosen that screw you can move the arm (with the two nuts). What is the purpose of that? if you loosen the set screw and move the arm what if anything does that do? I am asking because setting the 2 arms equal does not result in equal height in my case.

thanks in advance for any info or thoughts....