Very cheaply made, very flimsy. But I suppose you get what you pay for.
You have to take the cover off and the usual hexagonal 2 pin plug fits inside and then the cover shuts over it, effectively trapping the 2pin plug inside. But even when you've screw it in, it does not feel robust and the 2pin plug still shakes around so its not a tight fit, it's loose.
The fuse supplied with this is a 5A fuse even though it clearly states it's supposed to be 2.5A. I don't know what's wrong with the people who sell these, they clearly don't understand what fuses are for. Where the 2pins fit into the equivalent 3pin positions is relatively tight, so that should be OK.
To be perfectly honest I would look elsewhere for an adaptor.