NEW P90 10.4" BARREL, 1in9 TWIST, BLACK HARD MELONITE LINED FOR LONG LIFE. FULL AUTO RATED AND PRECISION MADE BY HDD. WE CHOSE THE MELONITE PROCESS FOR THE LONGEST LASTING P90 BARRELS MADE. BETTER THAN CHROME LINED. A VERY ACCURATE BARREL THAT CAN BE FULL AUTO FIRED WITHOUT DAMAGE. THESE ARE FACTORY SPEC P90 BARRELS WITH 12MM LEFT HAND THREADS.