For Two-piece, pancake-style zinc anode for rudders and trim tabs
Diameter: 5 1/8″
Thickness of One Half: 7/8″
Screw: Stainless Steel Socket Cap, 5/16″-18 Threads, 2-1/4″ Length.
EMP Zinc anodes conform to Mil-Spec: MIL-A-18001K

also crosses with:
Canada Metals CMR05
GLM 26655
Technoseal R5
Camp R-05
Reliance MDR-5