What is a Window Sheet???

[Bizzybee]

I very very new to this big new world of stamping and I'm enjoying so much looking at all the blogs and gathering ideas. I can't remember the blog I was on but I printed the picture of the box and the directions and it says to use a window sheet to make the clear box. Can someone please tell me what this is and where I might be able to get it???

Thanks bunches!!!
Kim:-D

[curias]

It is basically a sheet of acetate. SU used to sell them, but then they weren't happy with the quality. You can get plain acetate sheets at business supply stores that will work.