|This is the latest 3-piece design with barrel sizing sleeves! The SM-1 Modular Barrel System is the most precision manufactured barrel available today. 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 3-piece Stainless & Aluminum design incorporates a barrel-sizing sleeve system that's way ahead of its time! Simply use the included Barrel Tool (or any adjustable open-ended wrench) to help you unscrew the 5.5inch threaded choke from the stainless steel Sizing Collar, and you can re-size your barrel in seconds! Comes with 3 insert sizes: .686, and .689. and .693. The Aluminum Barrel Front is honed to a micro-polished .694. 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! Measures 14 in long overall.