Attaches just like the carbon 15 muzzle brake, exept it has 1/2X28 threads to accept whatever accessory you want, i.e. flash hiders, muzzle brakes, compensators, suppressors, and so on.
Similar to air compressor hose fittings. Extremely rare!!
Not availiable anymore.
$125 shipped to you.
Pic's available upon request. Unit snaps on the end of the barrel