Grovtec US Inc G-Nite Flash Suppressor 308 Cal 5/8"-24 tpi Black Nitride Steel The G-Nite Flash Suppressors Are Designed To Cool Down gasses And Suppress The Flash Signature. These suppressors Are solidly Made With Steel Construction And a Black Nitride Finish. Model: G-Nite Material: Steel Thread Pattern: 5/8"-24 tpi Finish: Black Nitride