Oh right! Daft gadget!
I guess it will do what any combi square will do but with more difficulty and at greater expense.
The dea is that you buy a thing like this which won't live up to its promise and then buy another one which might be better! Selling two tools is better than just one. Or three even, before you give up and get back to basics!
Couldn't find it on the web - do you have a link so that I can pour scorn on it?
You can get madder ones than that anyway - this is a good one
https://www.amazon.co.uk/Starrett-C434-12-4R-Combination-Reversing-Protractor/dp/B00002254L just needs laser technology adding.