Well they are a pretty neat design for starters. They do not have to fold backwards on impact to open. They slide back into place using a cantilever type action. This does two things. (1.) Requires less energy to open the head compared to conventional mech heads. (2.) It assures you that you will get a good sized entrance hole as it is impossible for this head not to open before entering the animal. Also the small fixed blade on the tip aides penetration and since it will have already penetrated about 1/2 an inch before the back of the other blades even make contact it should help prevent any problems with deflection on angled shots. I can also attest to the fact that they fly with field point accuracy.