This material is not specifically a Montessori one, but it certainly shares a lot of the Montessorian "spirit". My six year old loves it, and he has moved away from the pre-made puzzles he cherished at 4, to create designs of his own.
He calls them "my art project", and since they are non-permanent by nature, we take pictures of them before restoring the material. Here is one example:
I also use it for my 4 year old (and the 2 year old tags along) as a means to learn the name of the shapes and the colours.