What is it?
A bath shelf.
Why is it an example of good design?
The shelf unit is extremely simple in its execution. It has no adhesive qualities whatsoever, which makes it very easy to reposition depending on where the bath's occupant chooses to sit. Gravity and measurements alone are enough to keep it in place.
"If you think good design is expensive, you should look at the cost of bad design."
Ralf Speth
The choice of wood as the material as opposed to plastic or metals is aesthetically pleasing and creates an overall rustic feel, which might be preferred due to the relaxing connotations of a hot bath. Wood also softens somewhat when wet, which would help prevent damage to the bath itself if knocked out of position, as well as prevent scrapes on the surface.
To prevent the shelf from sliding too far left or right, the central portion of it is set lower than the narrow arms of the unit. The unit's width is also carefully measured to fit the width of varying bath sizes. The curved sections serve to minimise the chance of the unit knocking directly against the bath's rim. The shelf surface is also enclosed, preventing items from falling into the water below. Its bottom is also slatted, allowing any excess water to drip back through into the bath.