Easton 6.5mm Bowhunter Arrows (6 Pack)Hunting accuracy for shooter confidence is the cornerstone of Easton 6. 5 arrows. The 6. 5 uses proprietary Acu CarbonUniform Spine process. Acu Carbon is a continuous fed, single die manufacturing method that results in the most reliable tolerances and eliminates the need for the spine alignment and weight sorting. Easton's Acu Carbon production line produces the most consistent spine and weight from dozen to dozen and lot to lotyear in and year out.