The European number plate holder and light seems to be created to hold all the various different sized number plates used in Europe.
On my French plated Harley Davidson this resulted (I think) in an oversized holder that was quite ugly (see attached photograph), so I replaced it with a simple numberplate attached directly to the boot/trunk/coffre, and illuminated by a Thunderbike single LED (photograph attached).
I am very pleased with the resulting simple and clean look.