These are actually sheets of foam i found at an art andcraft store.Identical material used in Wilson Sophias andWatt puppies.I just measured and cut with knife and yard stick.they,re done at the same time I got the FSTs ,six months ago, my own version of lapels. they do help antidifraction. The tweeters are foam as they are more effective for the highs. Glad you like them, I apprciate it. thanks, Stan