The Bose WBP-8 bi-pivot wall brackets are for wall mounting the 402 loudspeakers. The steel materials in the Bose WBP-4 Bi-Pivot Wall Brackets are of pre-coated G90 material. The products are then powder coated. Thin surface scratches can be tolerated provided they're not too wide or deep. The pre-coating will provide adequate galvanic protection across thin scratches.