What is GAF #75 Base Sheet

Melinda Schlottmann and her husband are building a shop in Stagecoach, NV. They made a mistake when purchasing the roofing. What's important is they don't make a SECOND mistake. Here's what Melinda sent:

"We are finishing building a shop with a low slope roof.

We purchased what we thought was rolled roofing and after opening the roll and CUTTING a piece, my husband noticed it was not what he expected.  This is GAF #75 base sheet.

What is it and can we use it?  We already have felt over the plywood roof."

Melinda, don't use this product.

GAF GAFGLAS #75 Base Sheet is not a product made for exposure to the elements. It's made as a base layer to put under a membrane roof.

Click the link just above and read about it.

Take it back, exchange it, and get the right rolled roofing.