Increasing your gunâs performance is a must, and having an accurate barrel is number one priority. DYE UL1 barrels are made to the highest quality standards and are ultra-accurate. UL1 Barrels are precision honed to a .688 micron tolerance. Made from lightweight aircraft grade quality 6061 T6 aluminum for the perfect balance of weight and strength. Hard anodized to add a protective layer to your barrel for durability. Straight porting to keep your marker quiet and provide consistent airflow around the ball as it leaves the bore. Zero step diameter bore also ensures consistent travel. Unlike Most barrels, UL1 barrels are 3D contoured, shaving off weight without jeopardizing structural integrity.