This Foxtrot Mike Products AR9 lower receiver features a hybrid polymer design combining the light weight of polymer and the durability of aluminum. It features aluminum inserts in all the high stress areas to prevent breakage allowing it to last thousands of rounds. It features a last round bolt hold open and completely ambidextrous controls. It comes fully assembled with a trigger, mag release and bolt release buttons and features an integral pistol grip. Build your Glock magazine compatible AR9 pistol caliber carbine today.Features: Made from polymer with aluminum inserts Gives you the support needed to go with 9mm Glock style magazines It has a last round bolt hold open Ambidextrous safety and mag release Comes with a lifetime warranty Made in the USAAn American made product, the Foxtrot Mike Products Hybrid Polymer FM9 complete lower receiver comes with a lifetime warranty that will guarantee you quality performance for years to come.