K&rsquo;NEX Thrill Rides &ndash; Double Doom Roller Coaster Building Set &ndash; 891 Pieces &ndash;  Ages 9+ Engineering Educational Toy ENDLESS BUILDING POSSIBILITIES  Create an amazing roller coaster that stands 2.5 feet high! The KNEX Thrill Rides Double Doom Roller Coaster Building Set allows your children to explore endless possibilities and develop their creativity as they build a real-life working replica of a roller coaster. Alternative roller coaster models can also be built by following the downloadable instructions. This building set is recommended for children ages nine and above. MORE THAN 890 PIECES  This engineering education toy consists of 891 colorful parts of premium-quality construction. These include plastic rods and connectors connect to one another in different ways to build the Double Doom Roller Coaster. A track that serves as a railway for the two coaster cars is also included. MOTORIZED CONSTRUCTION TOY  Build your own ride and watch it come to life! This toy set comes with a battery-powered motor that gives life and action to the connected KNEX rods and pieces. Go beyond your imagination as you build and rebuild models that will take you on an amusement ride. This construction toy requires two AA batteries which are not included. CONVENIENT STORAGE  You no longer have to worry where to put all the parts and pieces after playtime. This set comes with a sturdy box for convenient transport and storage. Packaging may vary. STEAMagination: Its the connection of STEAM (science, technology, engineering, arts & math) with a childs natural curiosity and creativity and it powers the fun of each and every KNEX building set. Building with KNEX puts children on a path towards a fundamental understanding of STEAM/STEM subjects. THRILL OF THE BUILD: KNEX Thrill Rides allows each child to build bigger models that move to create an amusement park right in their home! Using the included parts and pieces, each KNEX Thrill Rides building set you can build a massive roller coaster, a majestic spinning Ferris Wheel and more  the heart pounding fun is only limited by your imagination. DEVELOPMENT BENEFITS: KNEX supports key areas of a childs developmental growth. As they click the different parts together and discover how the building system works, theyre strengthening hand-eye coordination, fine motor skills, problem-solving skills, spatial awareness and exercising their imagination! PARTS GUARANTEE: Broken part? Missing part? If you find yourself in need of a replacement for any reason, just give us a call! Well get you what you need so that your child can get back to building as soon as possible.