He didn't order it. He is quoting another Pinsider.
RVH - That part goes along the back orbit, where balls shoot up the center ramp, hit the bullseye, and then fall straight down to the playfield. On initial games all that they put there was mylar. After several months they started installing this. So if you have a game that still has mylar, you can reach out to Stern Support with your serial number and they will ship you this replacement part which provides better protection against the ball drops.