The Wilson Combat Adjustable AR Gas Block replaces a standard AR gas block and allows you to tune your direct impingement rifle's gas system for smoother cycling and enhanced reliability. This adjustable gas block is useful on match rifles, suppressed rifles and rifles chambered in non-standard AR calibers especially when shooting a variety of factory and custom hand-loaded ammunition. The Adjustable AR Gas Block is Chromoly steel with a Melonite finish that will easily hold up to high round count shooting and attaches to your barrel with dual set screws.