Stainless Steel Guide Rod Assembly S/S Guide Rod Assembly's are a complete drop in unit. Special features include: •Solid one piece stainless steel guide rod •Precision CNC machined to accept a removable 3/32 Allen head tip. •The ISMI recoil spring is manufactured of certified materials, heat treated for longer life, shot peened for stress relief and finally calibrated to Glock factory specifications 17 lbs for fullsize (17/22/31) and 18 lbs for compacts (19/23/32) •These combined features make the Lone Wolf Guide Rod Assembly the most durable, longest lasting system available today. Experienced shooters realize plastic guide rods can chip, crack or break resulting in feeding or ejection failures and guide rod flex can contribute to accuracy problems. The Lone Wolf Guide Rod Assembly addresses all of these issues and will provide you a life time of reliable service. TO USE IN GEN4 GUNS ORDER ADAPTER AS WELL