If you have ever tried to pull them out of target backwords instead of pushing them thru, you will see how easily the blades flex. Also if you look at the intial cut as they go into the target you will see a standard triangle pattern like any other fix bladed head. If they didn' t straighten on inpact you would get more of a circle pattern and I bet poor penitration. These are sharp and cut like a hot knife on butter. Real good results have been coming from the southern wild boar hunter.