How the Duo 4 was invented

You always need a pen to note something down. It might be a telephone number, a flight time or simply a good idea. You can borrow a pen at such times from the waitress in the restaurant where you are eating or the friendly cashier at the checkout. You can always find a piece of paper, if in doubt a receipt from your wallet will do.

Lots of people get a little inventive and offset this problem with a small pen that they carry with them in their wallet.

The Duo 4 is the second product developed for X47. The idea arose in December 2003 on a trip to Barcelona. The impetus for the Duo 4 was given by Matthias Büttner's wife, Bettina Sieg, on a long weekend away in Barcelona. “Why can’t we produce a DIN A7 booklet that we can slot into a wallet with your spring loaded spine rail? There we have the perfect solution: No looking for paper now – everything has its place!”

It was the birth of the Duo format, named after both functions that are combined here: the wallet and the organiser.

At the beginning, we created four different models: The Duo 1 without a coin pocket or cover flap, containing four credit card slots, a double banknote pocket and space for two or three spring loaded spine rails. The second variant, the Duo 2 expands the Duo 1 with a coin pocket, fitting on the exterior optimally. The point of contention: does the coin pocket belong on the left or the right hand side? According to the use, many of the test customers wanted the coin pocket on the right, and just as many wanted it on the right.

The Duo 4 equipped with a cover flap, six credit card slots and a double backnote pocket and – unlike the Duo 3 – also has a coin pocket. The Duo 3 is only sold in Italy, because, so the claim, Italian men always carry their small change in their pockets... After a lot of discussion, the Duo range was reduced from 4 to two models: the Duo 3 and Duo 2 have fallen by the wayside; the few pieces that have reached the open market will surely soon be found on collectors markets.