What is the part of a pick up truck that is the plastic part that goes around the top of the bed..............

.....and you can replace it with a black metal diamond plate oneWhat is the part of a pick up truck that is the plastic part that goes around the top of the bed..............
What?!What is the part of a pick up truck that is the plastic part that goes around the top of the bed..............
either a tanneau cover, or just a cap.

a tanneau cover is the flat one.What is the part of a pick up truck that is the plastic part that goes around the top of the bed..............
It's called a bed %26amp; rail liner. Yes you can replace it. Try partsexpress.com