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. Includes: 1 – Hardened 17-4 SS Guide Rod 3 – Flat wire Springs in 13lb 15lb and 18 lb weights 1 – SS Washer for Gen3 1 SS Captive bushing for Gen4 & Gen5 compatibility 1 Spring compression tool. For GLOCK G19 GEN1-5 G19X and G45