I think that is a construction of fibreglass and then riveted on...Don't think there is a replacement as such but its a DIY repair job if you have a rivet gun...Oh and some fibreglass..
Take it off, cover in parcel tape and use a fibreglass kit to take a mould from it. Add a few grammes (literally, 10g would be too much) of black pigment to some resin and lay-up a new one. Plenty of online resin, mat and pigment sellers about.