Digital BW, The Print

Today, I received ink and empty 220 ml cartridge for my 4000 printer,  
it took less than a week, great service from MIS.

However, when I look at these new cartridge, I don't understand how  
to refill them. I don't see any other holes than the outlet, is it  
here the ink goes in?
If so I understand I need some kind of adapter to fill.....

TIA,
danny