More spininng flights. The product name is 'Spiraline' but most sites will just call the spinning flights. I have only ever seen a few criticisms of this flight style. One was that they create more drag causing the dart to fly slower. If that is true then it doesn't seem to be a problem for me. The other is that you cannot put flight protectors on them because they will not fit. As you can see from the photo, this is not true. In fact I'd say it is pretty essential to have the flight protectors on spiraline flights because they are more apt to split since they angle in to a "V" shape.
As always, click the image for a larger picture.