The marble run coaster comes with 75 pieces and 30 race marbles (105 pieces in total). This colorfully fun marble run coaster allows for creative play as children and adults create their own marble run maze. The marble pieces help stimulate the brain as kids use their creativity to create endless designs. This type of building helps develop special skills and problem solving. Your kids will enjoy hours of fun creative play with this marble fun run. Peradix choose to use plastic marbles for 2 reasons: 1. It safer since glass marble tend to break, glass fraction splits may injure kids. 2. Plastic marble run slower in truck, it enlarge amusement and education. For reaching stable and high constructions, it is very important to have strong matching connections of parts, occasionally, mainly at first, it will look as not fitted, try with little more pressure, it will work. Pay attention in some cases marbles stuck or fall of trucks, probably this occur due to non leveled bases or not fully inserted item.