Galvanized steel insert with holes for bolt-on installation - 5/8" holes on 6" centers.
These anodes are built around a high-strength slotted steel mounting insert.
Unlike some competing brands, the steel insert in Sea Shield anodes is galvanized for longer shelf-life and better grounding.
• 1-1/2" countersunk holes
• Built to military specification MIL-A-18001
• Made in California, USA