Is 41 (EU) the max size for narrow beach sandals?

Checking the EU website for men's beach sandals. If I filter by Narrow, the max men's size is 41 EU.

Sometimes certain sizes are "out of stock", but for 42, 43, etc. there are simply no buttons, as if they don't exist. Even the size calculator said this model isn't manufactured in the suggested size. This is true for all beach sandals.

But it seems they exist on the US website.

Does anyone know what it means?

I'm trying to find shower shoes for my narrow flat feet.