Our Marble Mill Cascade Set can keep your budding civil engineer busy for hours! Crafted from Vermont-harvested hardwood maple, each piece of the set has terrific, non-toxic printed graphics that really give the set some appeal. The pieces are built on a 1.375" unit standard (think Unit Blocks). The Cascade Set comes with 42 wood pieces - 9 penstocks (different lengths), 1 lazy brook, 1 eddy, 1 catch basin, 3 "drops" (two overflow drops and one waterfall drop), 1 step rapids, 1 wave dip, a right and left bend, 15 stone pillars (for support only), and 8 small spacers. 18 different shapes in all that allow for vertical and horizontal building. All the pieces are modular so the set-up is endless. Comes with 10 marbles and packed in white corrugated box