I've worked on a few. It's been awhile but I've even done some warranty work on one. The customer brought me the bike and a replacement part and Landrider reimbursed her for my labor.

It's basically a Wallymart quality bike that has some sliding weights on the rear wheel that slide outward as you ride faster and move the rear derailleur. It saves you from the horrible bother and the excruciating torture of moving the shifter a click.

Along the same lines (answers to questions that nobody asked) I had a lawyer/customer who had acquired a warehouse full of 2 wheel drive bikes. They were department store quality bikes that had a flexible coupling that connected the front and rear wheels. He actually brought one in the box to my store (when I wasn't in) to assemble and display on my floor. When he wouldn't return my several phone calls, I threw it in the dumpster. A couple of months later he asked about it and wouldn't believe that I just threw it away. He got real mad.