NAP Crossbow Spitfire Broadheads have micro-grooved ferrules. Spitfire is undoubtedly the most trusted name in mechanical broadheads! Spitfires fly straight with pinpoint accuracy and perform better than any other mechanical thanks to the sharpest Diamize blades, and they stand up under the toughest conditions. The practice blades mean you can save your super-sharp blades for the big day. Super-durable hardened high carbon steel Trophy Tip The Slimline ferrule improves flight and penetration. The micro-grooves enhance accuracy and penetration. The snap-locking blade system holds the blades closed during flight, even out of today's fastest bows - no rubber exclusive Diamize Edge for a visible super-sharpness you can see Spitfire practice blades - save the super sharp blades for the field. NAP Spitfire Broadheads.