This is a Colgate Toothpaste Cap. If you lose the cap that came with you Colgate toothpaste this make a great replacement. It does not fit Crest. I have not tried it on any other brands. I have made a Crest cap here: https://www.thingiverse.com/thing:4752827

Nov/14/2017 - I have uploaded the 3D model files by request of maik10. They are in Autodesk Fusion 360 format. I also uploaded a Crest cap I modeled but every time I tried to export it as an STL it would become corrupted.