That rubber was "over molded" on the metal door. Basically the metal door was put in the mold and the rubber molded around it. To replace it the rubber would have to be removed and them molded onto the door again. So basically, there's no aftermarket replacement for these. I usually pick up a bunch of old beat up fresh air vents when I'm at the swaps and sell the good (or not so bad) doors out of them.