Fiberglass for roof valleys
Can anyone tell me about the use of fiberglass for roof valleys? I've only heard of using copper or galvanized metal. There's a long (over 35 feet) and deep (about 1 foot at the start) section where the two sections of my roof meet. Unfortunately, I wasn't home when the roofer inspected the project and wasn't able to ask questions. I can't even picture what the material might look like.