Saw these listed a few times online over the fall and ordered a set. My and DD used them today and were both very impressed with the easy of use and how it mimics a natural whip. We are going to try them with the kids that DD works with. Not only do they teach the whip but are a fun distraction that is sometimes needed. I ordered them from china so it took a while but they are available under the Rip Disc name.
Here is a video about them and a few more videos linked
Here is a video about them and a few more videos linked