The RYG Captured Gen 3 Conversion Guide Rod is an easy way to run a single spring guide rod in your gen4 Glock. This system doesn't require you to leave a plug in your slide but rather includes that as the washer for the guide rod. Currently this guide rod is available for G17, 17L, 22, 24,31,34,35 and G19, 23, 32, 38 and G20, 21, and 21sf.