Waking this thread up... I did a little investigation, the dust cap that Millersound is using as a replacement dome appears to be the same as (or similar to) the dust cap used in the Kappa and (believe it or not) SM series woofers. Due to the lack of support from Infinity for vintage products, I have to wonder who made these. Simply Speakers sells them and describes them as being "foam over screen". They are also available on eBay. Don't know if they're exactly the same as the ones used by Millersound, but I can't imagine many different folks manufacturing something like this.