A random dimensional model of a police helmet I did for using in my visualizations for projects I'm working on and understanding its measurements. Hope it'll be helpful for You!
3DM (Rhinoceros 3D, filesize: 28.2 MB), OBJ (OBJ, filesize: 207 MB), STP (STEP, filesize: 36.6 MB), IGE (IGES, filesize: 51.5 MB), 3DS (3D Studio, filesize: 38.6 MB)