London (CNN) -- When LEGO released a set of figures collectively called the Research Institute -- featuring a scientist, astronomer and a palaeontologist -- it sold out worldwide within a few days.
Why the fuss about a few tiny plastic people? Because they are all female professionals.
Previously, LEGO fans could only create professional females by building them out of existing parts. The only female figures supplied by LEGO fed into traditional stereotypes: Women hanging around the house, going to the beach or playing with pets.
But then in January seven year old Charlotte Benjamin penned a letter that went viral, criticizing the company for the lack of professional female LEGO figures.
"All the girls did was sit at home, go to the beach, and shop, and they had no jobs but the boys went on adventures, worked, saved people, and had jobs, even swam with sharks," she wrote.
This month, Charlotte got her researchers -- although LEGO said it was already developing the new female figures at the time of the letter.
Scientist Ellen Koojiman first submitted the idea for all-female LEGO set to the company's website on 2012. She managed to get 10,000 supporters for her proposal, which was eventually turned into the new product by LEGO.
"As a female scientist I had noticed two things about the available LEGO sets: a skewed male/female minifigure ratio and a rather stereotypical representation of the available female figures," she wrote in the pitch.
LEGO is now the world's top toy maker, after overtaking Mattel, the maker of Barbie. Its chief executive, Jorgen Vig Knudstorp, told CNN the company wants to expand in Asia and was eyeing markets such as China. "The idea of the LEGO brand resonates really well with the Chinese consumers," Knudstorp said.
"They are highly focused on creativity, learning, education, and at the same time recognize that learning trough play is a unique way of learning, which is in many ways much more powerful," he added.
LEGO has targeted the female market before, with its LEGO Friends set designed for young girls released in December 2011. The set, which revolved around close friends and featured a bakery, pet salon and juice bar, was criticized for pandering to gender stereotypes.