Easton 4mm FMJ 340 spine Carbon Shafts - 12 Pack - The 4MM FMJ offers the most penetration and is precision-made in USA for the most accurate hunting arrow on the market. The 4MM Full Metal Jacket has been updated with a new spine configuration, an all-new 8-32 point outsert system, and a redesigned graphics. The standard 8-32 thread point outsert optimizes front-of-center for easier broadhead tuning and more durability. FMJ starts with an advanced carbon core foundation for lightweight strength. A full metal jacket adds kinetic energy, enhances accuracy, and pulls easier from targets. The combination provides the deepest penetration and more pass-through impacts for quicker kills and heavier blood trails.