Shakeproof Lock Washers Internal & External Toothed Serrated Toothed galvanized. Size: M3 M4 M5 M6 M8 M10 M12 M14 M16 M18 M20 M22 M24. Types: Internal Toothed & External Toothed. Serrated lock washer-- external serrated lock washers are mainly used for small parts, which can effectively prevent loosening.
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