Gillette OLD type.

[antdad]

I don't have one but I'm assuming you also need old type blades if you ever want to shave with it?
So does that make them collector's pieces only?

 

[hunnymonster]

I don't have one either - but I understand that modern blades fit and work - sometimes there is the potential for chatter, but you can use a cut down second blade as a shim to stop that...

 

[fozz77]

HM is bang on. You have to pay attention to the blade alignment as well. not a bad little razor actually

 

[merwtje]

You don't need a shim to get a great shave with an Old Type.
The blade gap is rather small.