I have just found out what this stuff is even called (the local stores just shrugged and weren't helpful so I had to look online) and almost every window in my house has at least one strip of this that is cracked and falling apart (very brittle) so I need to replace it but don't know which one to order. I'm attaching a couple of photos of a piece that I was able to take off one of the windows. I hope they are good enough to help with the ID. It was hard because it was so brittle that it fell apart easily. :-(
