Originally used on oil lamps in America during the mid to late 19th century
Made In USA
Shades are measured by bottom diameter, across the base.
Bottom diameter is slightly less than 12", which is normal.
11-3/4" Bottom Fitter
12" Opal Lampshades are large size student shades used on hanging lamps and big table lamps. Complements many Victorian lamps. Glossy white color produces great light when lit. Use on lamps with 12" shade holders.