That's blackout cloth. Many people use it as a first DIY screen material. (Still have mine after 3 yrs.
)
It's white. It's used as a *liner* behind real drapes, to "black out" any light coming through the window. You could use it as cheap drapes but it's pretty basic.

It's white. It's used as a *liner* behind real drapes, to "black out" any light coming through the window. You could use it as cheap drapes but it's pretty basic.