It is a special box or a functional unit. When you drive the handle(or the bolt), the four blades open or close gradually. It is not lightproof，and it is not a gear reduccer . You can assemble it other parts by bolts with 4-M3 bolts. It can be considered a gift box design plan.The size is appr. D114X67mm(diameter x Height). To assemble the box, you need to prepare some metal parts: M3X12 screw, M3 nut, M3X16 screw. Parts are designed for 3d printing.It is best to use resin material when printing. And due to the part's quality, there may be some hand work. You can get the newest discount code from sidebar here: https://www.tanerxun.com/blogSTEP files are included. You can ignore the fbx,stl and obj files, they are just for cgtrader's requirement.