Preowned all pieces and instructions present. Only thing from being just open box is the stickers are partially applied Circuit Explorer® teaches the fundamentals of circuitry through out-of-this world playsets kids can build and power themselves. By following the simple circuits and harnessing their imaginations, kids 6+ can use the system-ready pieces to construct their creations, connecting them to STEM-based learning as they play. Review: I bought this for my 6 year old daughter that loves building with legos. We wanted to give her an intro to building circuits (her father is an electrical engineer.) We just love these circuit explorer sets. In the booklet, the kids receive a mission to build a space station on Mars. My son, who is 4, is also obsessed with these sets. My daughter loves following the instructions to build each structure recommended, but also loves to build her own creations. The creations light up, move, and have cool sound effects. My son spends the day pretending the rocket ship is lifting off into space. He loves the sound effects and that he can record his own voice to be synthesized. I love that I can use this to help teach lessons about Mars, space, and circuit building and electricity and then let them play on their own. It's super engaging and I feel like they can play with this all day, especially on a cold day when you can't play outside as long. This is the perfect Christmas gift. I love that you can keep adding more sets. I knew that this