its quite simple cozmo, if you've seen a the struts in your car, or ever changed shocks that have inserts in them, you'll know, as i'm sure you should. holds the top of the insert centrally at the top.
when i brought my car, i used to always have a bad knocking metal on metal noise going over bumps. i looked for ages, then eventually put it down to shocks, (this is the front by the way)
so we took them out, brand newish kyb shocks, bu some dickhead had hacksawed off that bottom bowl thing that holds the bottom of the shock centrally in the strut, then on the top nut, VERY DODGILY, welded a smaller spacer in the one that screws into the strut

. so the top of the shock was alwas moving in the strut and banging all the time
all in all it would've lowered it an extra 5-10mm, and f#cked a perfectly good set of shocks
so replaced them new kyb inserts, got rid of 95% of the noise, then found needed bump stops in there, nows its smooth as. car was supposedly professionally lowered too.
some people
