Quality CNC machined Recoil Spring Assembly for Glock™ Full Frame pistols G17, G17L, G22, G24, G31, G34, G37 and G20, G20SF, G21, G21SF Completely assembled "drop-in" unit includes ISMI™ heat treated, shot peened and stress relieved premium chrome silicon springs. Offered in either Black or Polished exposed face. All guide rods are stainless steel and have a 100% lifetime warranty. Recoil springs have a one year replacement warranty. Both are made in America.   *If you are going to use this Guide Rod in a Gen4, you will need the Gen4 Guid Rod adaptor!* *Sold Seperatly*