Lego Duplo (trademarked as DUPLO and stylized in the logo as duplo) is a core product range of the construction toy Lego by The LEGO Group, designed for children from to 5 years old. Duplo bricks are twice the size of traditional Lego bricks, making them easier to handle and less likely to be swallowed by younger children. Despite their size, they are still compatible with traditional Lego bricks. Initially launched in 1969, the Duplo range has expanded since then to include sets with figures, cars, houses, and trains. Duplo products are manufactured in Nyíregyháza, Hungary. Development Before its introduction in 1969, The Lego Group investigated ways to produce safe, age-appropriate Lego bricks that were larger in size than traditional bricks in order to target young children aged one-and-a-half years and above. The company initially struggled to find a scale that would fit with the existing Lego System of Play, exploring 3:1 and 4:1 scales, but eventually settled on a 2:1 scale. In 1968, second generation owner Godtfred Kirk Christiansen provided the idea of hollowing out the studs on the Duplo bricks to make them compatible with the system. Duplo is derived from the Latin word for "duplex", meaning double. Launch and release Duplo bricks were introduced in 1969, in four colors: red, yellow, blue, and white. The following year, two more sets were added with blue and red wheel plates. In the product catalog for 1971, the sets were described as being for children from 1 to 2 years, but were still sold mixed with Lego bricks, normally designed for ages 3 to 12. In 1972, the Duplo brick with two rows of two studs was introduced. In 1975, Duplo became its own product brand, with five sets made up exclusively of Duplo bricks. New additions included a round-topped two-by-two stud brick and a small four-wheeled wagon with two rows of six studs. With these new Duplo sets, Lego began targeting children years old with the intention that when the children became older, their Duplo bricks could be used together with regular Lego bricks. In 1977, the Duplo name was dropped in favor of Lego Preschool. Small figures the size of two-by-two bricks were introduced, made up of a cylindrical head and a tapered, limbless body, similar in design to Fisher-Price's Little People. Another new brick was a half arch. The new sets included figures, doors, and two-by-six brick