Z Guard Aluminium Hull Anode Bolt on disc 140MM dia. KIT The kits come with the anode, a deep polyethlene backing pad, M10 nut and serated washer. Sold in single quantities. Box size: 10. Since 1977 Z Guard has manufactured sacrificial anodes for the major UK boat builders, lifesaving organisations and other recognised trusted UK brands.  Z Guard has an unrivalled proven pedigree, DNV-GL certified & produce to military specifications Mil-A-18001K, Mil-A-24779 & Mil-A-21412A.