QUATRO (0 parts)
A retired LEGO product line for very young kids featuring blocks that are twice as large as DUPLO.
At four times the length, width, and height of a normal LEGO brick, QUATRO bricks are 64-times the volume of the equivalent LEGO brick which is why they feel enormous.
To create huge models, you can attach a standard DUPLO 2×2 or 2×4 brick on top of a Quatro brick (and LEGO bricks on top of DUPLO).