So I've had a couple prototypes of these for a few months and overall I like the concept. Unfortunately I haven't been able to shoot an actual deer with them but a few of the guys at NAP have and reportedly they've worked well. The idea is that when shot the leading blades begin to close as they enter the animal, which opens the rear blades. Then as the rear blades have pressure applied on them the front blades redeploy. I guess it's kind of like a scissoring action. As one blade encounters resistance it's forced around the obstacle, which pushes the other blade back open. It will be neat to see how they perform once people get them in their hands and start using them this Spring and into next year.