I have never seen anybody else use one of these around these parts they are a great little call!
https://www.midwestturkeycall.com/slate-calls/2067-do-ral-sassy-slate-call.html
Interesting design. I don't think I've ever seen one. I like the one hand operation aspect.
Is there a video somewhere on how it operates and sounds?
There is not a whole lot of information online, here are the directions that I have from some of mIne.
(http://i64.tinypic.com/11qipt3.jpg)
If you Google them there are some comments from other hunters using them. There are four different models. I think one guy makes them up in New York.
The only reason I know about them is because they used to sell them at the L.L. Bean store in Maine and I happen to pick one up there other than that I have never seen anyone else using one and there are not many places to buy them.