10" fitter, Opal Glass Shades
Keep in mind.....
.....the fitter referenced for glass shades (such as a 10" fitter) refer to the size of the shade holder and not to the exact size of the lamp shade.
The glass shade will measure slightly under the "fitter" size to allow the shade to set in the fitter and not on top of the fitter.
So, a 10" shade will actually measure between 9-3/4" and 9-7/8".
These Glass Shades are commonly known as Student Shades.
The 10" shades most commonly fit Antique Lamps such as
Aladdin, Rayo, Bradley & Hubbard, Miller, etc.
or Reproductions of Antique Lamps.