Most adjustable guide rods on the market use a cap screw to retain the spring. The problem? Loose screws are too common and thread locker forces you to commit to one spring weight. Enter the screwless design of the COMPRESSOR Quick-Tune Guide Rod. The dovetail interface is captured by the spring, creating a simple and secure lock-up. Flutes along the guide rod allow the spring to move with less friction for smoother cycling. The heat treated guide rod has a slick, durable, and corrosion-resistant Nitride finish.Features :Screwless DesignFor GLOCK G19 GEN1-5, G19X, and G4513, 15, 18LB Springs included