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. Adjusting your rifle's gas port will lower or increase your bolt's cyclic rate and tailors your rifle's performance to your unique needs. 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. A simple adjustment of the locking hex screw at the front of the block lets you control the gas volume so you can tune your rifle's function to your favorite loads. The Wilson Combat Adjustable AR Gas Block is Chromemoly steel with a Melonite finish that will easily hold up to high round count shooting and attaches to your barrel with dual set screws. It is compatible with all standard USGI pattern AR rifles and DPMS pattern LR-308 .308 AR recievers that take standard length gas tubes. Lo-Profile gas block requires 1.45" internal clearance to fit under rails. The package includes: adjustable gas block, adjustment set screw installed, straight gas tube installed with gas tube pin installed, 12" long Allen Wrench to adjust inside handguard.