QUATRO, Brickipedia
LEGO QUATRO was a theme in preschool series introduced in 2004 and discontinued after 2006. It was designed for children age 1 to 3. QUATRO bricks, hence the name, are designed to be twice the dimensions of LEGO DUPLO bricks. The name "QUATRO" also signifies that the blocks are quadruple the dimensions of the traditional LEGO System blocks. QUATRO bricks are compatible with DUPLO and System bricks. These pieces were baby-friendly, and were specially designed to endure teething. In addition, they
5561 Big Foot 4 X 4 - Brickipedia, the LEGO Wiki
LEGO compatibility with Duplo, Quatro, and even bigger LEGO bricks
5431 Roll 'n' Play, Brickipedia
Queen Beast - HEROsector01
1702 Fire Fighter 4 x 4, Brickipedia
Lego's Worst Failures
LEGO compatibility with Duplo, Quatro, and even bigger LEGO bricks
Fabuland Figure Raccoon 4 - Brickipedia, the LEGO Wiki
LEGO minifigures Elves
LEGO Star Wars Sets: 7166 Imperial Shuttle NEW-7166
Lego's Worst Failures