By registering their subjects in an identical framework they provide an almost scientific record of people's attempts to distinguish themselves from others by assuming a group identity. The apparent contradiction between individuality and uniformity is taken to such extremes that the artistic aspect dominates the purely documentary element. Rotterdam's heterogeneous street scene remains a major source of inspiration for them, although they have also visited Milan, Beijing, Rio de Janeiro, Casablanca, Praia (Cabo Verde), New York, Bordeaux, London and Paris.
 
For this anniversary edition they made 18 new series in the Rijksmuseum Amsterdam, the Hague and St. Petersburg.