Check the pics there are no cups on my struts. Its fully flat and also the spring sits snugly over the body of the strut so there cannot be any torsional movement on the bottom. it will be flat metal surface against flat rubber surface and the rubber surface will cradle the spring so the spring doesn’t slip of the rubber. The springs fit tightly around the shock body at the spring seat one the top hat is on there is absolutely no moving the spring in any direction. Those twist in things have to affect how the spring operates. Those seemed mad sketchy to me. I’m basically just lifting the bottom of the spring up with a hard rubber .5" spacer. Apparently alot of Saab 9-5s use there because of suspension problems in the rear so it should be a non issue
This is going to be used pretty much as a spring seat grommet, but I guess they can also be stuck between top coils on a sagging spring to re-lift the car and gain back spring ride quality (i think that is sketchy)