World's smallest cube

This must surely be the smallest commercially available 3D puzzle cube in the world.
It is a tiny 7.5 mm across and presents a real challenge to solve and take apart - and not just because of its size.
It is an example of a sequentially interlocking cube which means that it won't fall apart once the pieces are slotted together.

The puzzle was inspired by the cover of Elbow's brilliant album, The Seldom Seen Kid.