About this 3D model

These things help putting a small fan into a bigger hole. They are simpler than the ones in http://www.thingiverse.com/thing:21112 and I made them 'cause the 40to30 file in there has size errors. The designs are made in CATIA v5, and I uploaded both the CATpart and a converted STP file to help derivative works. By now, I have 40x40 to 30x30 and 80x80 to 40x40, but I can made any other size if someone asks for it.