A very great replacement for any buffer spring that comes with the lower you may buy! - Geissele Super 42 Rifle Length Spring

It's a great buffer spring so far, the pull on the charging handle is a little stronger because of how the spring is made, but the is a slight negative the greater benefits of it. The rattle can noise is completely gone, and it definitely reduces the recoil of the weapon overall. Definitely an inexpensive upgrade to get when you can.