I bet you will be sorry you asked.
The box takes a standard U.S. 220v 30a dryer circuit and breaks it into two outlets, both fused to the lower amperages used by Euro machines. [A 30a fuse or circuit protection would not adequately protect the machines' smaller gauge wiring.]
Although the Euro dryer is fitted with a larger plug (probably emulating a "std" U.S. 30a one), we can see that the washer has a smaller 15a or 20a one.
Instead of the machines getting 220v between a hot (phase conductor) and a neutral (ase seen in Europe and other parts of the world), they are getting American Style 220v between two hots.
So in short all it (the box) does is break one outlet into two and fuse them at a lower than 30a amperage. I would assume thatt to be 15a or 20a.
An American washer with a Euro dryer is a bad idea, Slow spins and slow, smaller dryer (circa 2,500 watts).
A Euro washer (fast spin, traditionally smaller capaciy) with an American (fast, large) dryer [5,000 watt +/- heater] is a better combination. But using an electric American dryer will mean the full capacity of the std. U.S. 30a dryer circuit is needed and then a Euro washer will need a dedicted 220v line, which this box attempts to avoid!
Canada uses a system nearly identical to the U.S. and is meant to be included when I say U.S.