you are referring to the bumpstop in the middle i assume. I'm not sure if you are asking about the compressors working or the pucks. once you take the spring out the new spacer as a hole in the middle and it slides up that to sit flush with the body. if you are asking how the compressors work, there are two. basically a threaded piece with a bolt head and a "hook" on each end. place them both on the coil opposite each other and compress! always take your time and be careful. its nice to have a friend help you too.