This is a Stirling engine kit that you assemble while learning about science. It is new and unopened, but there may be rust or dirt due to aging. The outer box also has some stains (see photos). Please be aware of this beforehand. If you wish, I can open the box and take photos of the contents. - Product Name: Stirling Engine - Parts Contents: Engine parts, gears, propeller, etc. - Instruction Manual: Assembly instructions included - Brand: Gakken Thank you for looking. Thank you.