DYNAMIC SPINE CONTROL - Patented high-tech carbon material construction that manages dynamic spine in a new way to make broadheads fly better. Maxima RED SD uses different carbon materials to control arrow flex to the RED ZONE SMALL DIAMETER [SD] - Features a .203 inch inside diameter for better penetration and less wind-drift. Available in 250 and 350 Spine Sizes RED ZONE - The section of the Maxima RED SD arrow shaft that manages arrow flex in flight, which is called dynamic spine. The RED ZONE is the best section of the arrow shaft to contain Dynamic Spine and make broadheads shoot best ACCURACY - Broadhead moves the center of mass forward on an arrow, increasing the flex of the arrow. The shape of the broadhead acts like wings on the front of the arrow. The stiffer front end of the arrow shaft repositions arrow flex to the Red Zone REDUCED OSCILLATION - Reduced oscillation on the front end makes broadheads shoot more consistently and enables more accurate shots at longer distances › See more product details