This is a non-WCA twisty puzzle that is similar to both a windmill cube and a mirror cube, hence the name windmirror. It is basically a "mirrored" version of a windmill cube. That means it is a windmill cube where the layes of the puzzle are different sizes. BTW, I took this picture in the middle of my nature collection for some reason, so that's why there are so many shells and fossils etc, but the puzzle is the silver one in the middle. It solves similarly to a windmill cube, which solves similarly to a fisher cube, which solves similarly to a 3 by 3. If you know how to solve a 3 by 3, chances are you will be able to solve the windmirror cube.
Of course, if you can't solve it, don't worry. Click here for a solution video!