They were designed to put more shells in a tubular magazine. I got some one year and they were a lot of fun. I have since been using the Rem 8.5 managed recoil 7/8 loads for the same purpose.

I do not remember seeing them at the shot show last year in Orlando but they are usually there when it is in Vegas. I believe that they are a Mexican company. They usually have a nice model at thier booth.