It is a necking mechanics or shrink mouth mechanism. Parts are designed for CNC machining. The center hole's diameter is 55mm,so the max diameter of pipe that you would shrink is 50mm. What you will get are design files, including DWG drawing, pdf, STEP(3D model) files. The red parts in the hole center can be customized, you can change these parts as needed to meet your requirement.The whole functional unit can be assembled on other part with some M8 bolts and locating pins. To use the mechanism, you can prepare a handle by yourself. Or you can design and machine some other parts too.You should have basic mechanical knowledge to manufacture the parts.Ignore the FBX and OBJ format files, they are only used to meet the platform's requirement.If you need a 3d printing version,visit: https://www.cgtrader.com/3d-print-models/hobby-diy/mechanical-parts/d25b6nm-necking-mechanics-for-3d-printing-diy-idea