They are pure trim, but they are the piece that shows every scratch and every broken clip, and an ill-fitting bezel makes an otherwise clean interior look damaged.
Bezels are replaced when a clip has snapped and the ring no longer sits flush, when an aftermarket radio installation has cut or cracked the surround, or when the finish has worn through. Because they are thin mouldings, they crack easily during removal, which is why a repair often ends with a new bezel.
Match by position and by option content: navigation or plain radio, with or without a centre speaker, automatic or manual climate control. Each combination changes the aperture. Colour from the trim code, and check the clip positions in the listing photograph against the old part.