Elong 6/12PCS 30" Arrows for Compound Bows,Pure Carbon Hunting Arrows for Archery Spine 600/700 with 100 Grain Screw Tips,4" Turkey Feathers

These are good looking arrows I really like the heat shrink(?) tubing at the top of the fletching to prevent tear-offs.However, one of six arrows cracked, so that the nock fell out. This happened after shooting for an hour using a 25# bow shooting at hay bales. We are beginner archers, but I'm guessing this is not normal behavior for new arrows. I know that you're not supposed to shoot cracked arrows due to safety problems. I will be watching the remaining arrows very carefully to make sure I don't get them shattering or worse, impaling my hand.UPDATE: changed to 1 star. After 2 months of use, all the arrows developed long cracks in the shaft, normally around the nock. They are low price arrows. I definitely did not get value for the money though. I thought I'd try saving a couple bucks over victory arrows, but these definitely don't last. I will salvage fletching, tips and inserts for future use.