Restore Infinity RSIIIb RS3b Acoustic Foam?

I'm trying to find replacement acoustic foam that is on the front speaker surface around my Infinity RSIIIb EMIT tweeters and Polycell Midrange. This is not the speaker surround but an acoustic foam rubber (similar to neoprene but not neoprene) around them. It's so old that it's disintegrating, which is natural and seems to be the case with any RSIIIb photo I've seen. It's about 1/4" thick. Thanks!