The Magpul Enhanced Self-Leveling Follower is a drop in replacement for the aluminum USGI 30-round magazine black or green follower. Featuring a patent pending 4-way anti-tilt design for increased feeding reliability"" the Enhanced Self-Leveling Follower is made from a non-hygroscopic and self-lubricating polymer. NOTE: Will not fit the latest generation USGI spring that is utilized with the tan or blue (EPM) follower. Also not optimized for thin-walled steel-bodied magazines.