9mm 1/2x36 Flash Hider
If your building an AR-9, and don't plan to run a suppressor or some fancy muzzle brake, it doesn't get much simpler that a standard flash hider. This flash hider is cheap and effective, and tapped for 9mm 1/2x36 threads. I used this flash hider on a budget AR-9 build, and it keeps barrel rise in check.