For the sheet of ten self-adhesive Personal Stamps with square images, PostNL has opted for a new series on mammals in the Netherlands. In 2013, four of these stamps will be for sale in all PostNL post offices throughout the country: the squirrel (2 January), the fox (25 March), the common seal (22 April) and the red deer (12 August). A remarkable aspect of the new self-adhesive stamps is the use of a new technique to peel the stamps from the backing paper. By means of perforation and the use of the so-called break-slit, stamps can be removed from the sheet even more easily. An additional advantage is that it is virtually impossible to tell the gummed and self-adhesive versions of the Personal Stamps apart.
With the series Mammals in the Netherlands, PostNL introduces a follow-up to the previous series Birds in the Netherlands. Both series were designed by design agency Excello in Gouda. Designer Martine den Boer: "The series Mammals in the Netherlands consists of 36 mammals, which are all shown on the stamps in close-up. Each mammal looks you straight into the eyes, curiously, but sometimes also with a certain pride. The portraits have a soft-focus effect, making the animals look friendly and almost cuddly. The trail pattern of the respective animal is printed on the margin of the stamp sheet. It shows that squirrels are bounders: their hind paws come down in front of their front paws."