I haven't measured mine, but the 3.8mm one looks an awful lot like the one I have from DX. I use this in Denmark, which use standard EU-type plugs.
My guess is that both plugs will work(the 4.8mm one is from EU to US - so it converts the wrong way).
Otherwise you can just buy an empty EU-type plug at your local builders-marked, and attach it to the wire.. The converters you need are just to change the physical appearance of the plug - it doesn't alter the electricity at all.
Take the 3,8mm one. I have both (not from Manfont, but I think all shops get the same items). The 4mm is a little bit to big and some US cables don't have a great connection to it and slip out of it.
I have bought a few of these on Ebay.. They work well!
Youll actually dont need the long cables anymore! I got a few of those (US plugs, not the EU) and used them on my chargers, and for my Laptop! because I was getting annoyed with all the cords getting strangled, when putting them in a storage box!
Edit:: changed the picture..
I think they are about 1 dollar each.
here are some on sale, HERE for 99 cent. in Euros maybe about 80 cent?
Just search on ebay for: EU ac adapter macbook
If you want those plugs you showed from manafont, they are going on ebay for about 10 cent each...
always handy to have a few. I got a few for 1 cent ;) when bidding.