|The newest addition to SM-1's line of barrels, this 2-piece All-Aluminum design reduces weight, but still incorporates their performance-enhancing inner-diameter sleeve sizing system! The SM-1 Modular Aluminum Barrel is manufactured to the same precision tolerances as their top-of-the-line 3-Piece Stainless System, and is every bit as accurate. Unlike many mass-produced barrels today, the SM-1 is built in small batches by a Southern California manufacturer who supplies several local teams. Its unique 2-piece All-Aluminum design incorporates a barrel-sizing sleeve system that's way ahead of its time! SM-1 includes their most popular sized sleeve, a .689 inner diameter, which is made for super-accurate shooting with name-brand paint. You can also purchase their sleeve sizing system separately, which includes 3 more sleeve sizes: .679, .683, and .686. The main shaft portion after the sleeve is honed to a micro-polished .692. Paintball experts all agree that the key to accuracy is improving ball to barrel fit, and this barrel system, will help you achieve your goals!