Typically, a shotgun choke (fixed or screw-in) has three basic sections: the entry, transition (constriction), and exit. The entry (the bore section) and the exit (the muzzle section) have parallel walls and the transition is conical. With most manufactures, the angle of the cone is fixed and its length varies. The longer the conical section, the more constriction there is. This is not the case with the Poly-Choke. With adjustable collets, the transition is not conical, but curved. The more constriction, the tighter the curve, and the more off-axis its terminus. I'm skeptical about their claim,"Testing proved to pattern as good as or better than factory choke tubes." If this were the case, why don't we see them used on comp guns?
Oneounceload's comment about added weight at the muzzle is valid. However, I suspect the same thing may be said for some of the monster extended choke tubes on the market these days. Many shooters may not have the experience to evaluate their gun's swing characteristics. My first shotgun came with a Poly-Choke, and I shot a lot of holes in the sky with that gun. For the casual shooter, a Poly-Choke may be a viable option to a pocket full of expensive screw-ins. For me, no thanks… been there, done that.