In the style of the standard A2 “birdcage” Flash Hider, this version – sized for the .308 – has 5 vents machined around the sides and top. The bottom is closed so as to avoid a tell-tale “dust signature” when shooting prone. It is machined from high quality steel, threaded 5/8″ x 24 T.P.I. (threads per inch) pitch and finished in Black Phosphate. Install this with a crush washer to properly “time” (position) the venting slots.