The A2 Extended Flash Hider from Schuster Manufacturing is based on the original M16A2 design (solid bottom to prevent dust from kicking up). The difference is in the length. The Extended A2 has enough added length to will ensure that your 14.5" barrel will measure at least 16" after installation.
The flash hider must be permanently attached. This flash hider is NOT pre-drilled for a pin, weld, etc. 1/2"-28 threads.