Hi Barb...I thought it was going to be goretex for the final material until day before yesterday when the doctor said it had changed from what he told me last year and they're using, I think it's called alloderm which I think he said would be good for a minimum of 2+ years -- I gather that that's as long as they've used it. It's lucky I was delayed!!! I don't know why the switch. But so far, so good...Liz S.