LanTac USA LLC Guide Rod Adapter Bushing, For 4th Generation Glocks to Utilize 1-3rd Generation Guide Rod and Spring, Nitride Finish, Black 01-GP-GRA-NIT Precision 17-4PH Stainless Steel Adapter Bushings with ultra smooth bore and crenulated crown" for reduced friction performance and aggressive styling. Designed to work with 1-3 Gen Non Captured Guide Rod.