after using death sticks for many years i decided to upgrade my compressors, these are so easy to use, on real effort needed to compress the spring. uses a 22mm ratchet, DO NOT USE AN IMPACT GUN THIS WILL DAMAGE THE THREAD. but remember to grease the screw thread before first use, the yellow plastic stays on, DO NOT REMOVE, it hold the spring in place, someone no here said you remove it but that is false. the only criticism i have is vevors customer services ask them what type of grease 5 days ago still no answer, i used spray white grease works fine.