Peke

You can make a shape of a cross (X Pentomino) with these pieces.

The shape is arranged on the cover of its guide.

The pieces can form other shapes, which are shown inside the guide, like this:

Green one is made as its prototype, and yellow as a personal gift.

Here is wooden version crafted by Saul Bobroff, which has an additional rule.

The rule is to use each piece upside the face of the same color.