CITY BUILDER – 325 PC/ 20 MODEL BUILDING SET – Introduce your children to endless building possibilities with the K’NEX Mega Models Building Set! This building set from K’NEX comes with 325 different rod and connector pieces, which can be assembled into 3D configurations. Kids can follow instructions to create 20 different model ideas including: a Skyscraper, a Castle, a Treehouse, a Arch Bridge, and much more! Help your kids develop a better understanding of STEAM (science, technology, engineering, arts, and math subjects) with easy-to-follow instructions.