Twist and Flex test, Grab the top and bottom of the arrow and twist it, then rotate it, and twist again, till you have gone all the way around the arrow looking for small cracks or little bulges in the shaft. Flex test you do the same thing only you flex it like a fishing rod. If you shoot more than one carbon arrow at a single dot or 3D target you better be checking them all the time. Also carbons loose their spline, and will no longer group with the rest of the arrows, Just another reason to heavyer instead of lighter and keep them all numberd, you can tell when something is wrong faster!