Protect your engine against galvanic corrosion by changing its anode regulary.Anodes may be purchased as a complete assembly (anode with brass plug) or as a replacement anode only. Threads for replacement anodes (which screw into the plug) are NPT.” Outside threads for plugs (which screw into the engine block) are UNC”. Length” refers to visible portion of anode when installed in plug. Offered in zinc alloy only.Key FeaturesChoice of brass plug with anode or replacement anode onlyLength” refers to visible portion of anode when installed in plugThreads for anode are NPT;” threads for plug are UNC”