Gillette travel/lightweight head.

Evening, gentlemen.
Some if you were kind enough to help with an identity query recently. I've just spent over £2 (two) on a lightweight Gillette DE; with its handle it can't weigh more than 40-50g.
I'm intrigued by the "31" on the underside: can anyone please explain it?
Thanks and best wishes from East Anglia,
Steven.
P.S. In the photos, the paper is white and the metal is silverish, I'd say certainly aluminium for the base and handle.

Tech, 1960s or 1970s I think. The 3-1 ought to be a date code, but someone made a mistake. I think the UK operation picked up date codes fairly late in the game, which might help place this example.

Thanks for the reply, mblakele.
It does feel so very light: I'll try it with the original handle first, but it feels more like a razor with an Edwin Jagger rod on it.

Thanks, topcatman. What do you mean by "zamak" head?

Zamak is an alloy, the name is an acronym for zinc, aluminum, magnesium, and copper (k cause its a german thing). It's not nearly as durable as the plated brass used in most vintage razors.

Thanks, Brad.
Whatever it is, it gave a very good shave attached to an Jagger 89 handle (new Astra green blade, Wool Fat soap). It somehow felt sturdier on the face than in the hand.
Best wishes,
Steven.

The only warning I can give about that head is that it gets extremely hot if you soak it long enough in hot water.[/QUOTE]

I can see exactly what you mean, topcatman. If I want razor burn, I'll get the old-fashioned way by shaving badly...!

There's several posts on here about people loving the shave from a travel tech. I have one myself I haven't tried yet. You might want to dab a bit of petroleum jelly on the threads, as that's a weak point for zamak razors, and dry it after use.

Thanks, Brad: will do.