The Torchiere lamp glass shades that we carry have a 2-3/4 inch diameter neck that is about 2-3/4 inch long. The 2-3/4 inch neck of the torchiere glass shade fits over a Mogul Base Socket (SO8601), as seen on most older floor lamps. There are no screws that hold the torchiere glass in place. Always hold the torchiere glass shade with two hands when handling the glass shade.
This is a measuring guide for shades that fit this description -
If the holder does have screws, most likely it is an IES Glass Lamp Shade. IES glass shades IES Glass Lamp Shades are commonly used as reflectors for cloth lamp shades on floor and table lamps. The cloth lamp shade frame usually has indentations where the shade sits on the glass shade.