500 Spine/.004 straightness/,165 ID/Patented R.O.C System 60 grains. The Onyx is one of the best hunting arrows ever designed. Our proprietary Rugged Wrap construction process provides a much thicker carbon wall than competing shafts, which makes the Onyx one of the toughest arrows ever built. The micro-diameter means greater penetration and less wind drift. With the Onyx, you have the perfect combination of accuracy, toughness, and front of center.Onyx Arrows come equipped with Blood Ring Certain Shot Technology that will reveal what kind of hit was made using the age-old logic of blood types, shown on the white Blood Ring panel after contact with your target has been made.