UEF testing approved for DOE;Brass nipple connection Diptube and Hot Water outlet;2" high density blanket-type insulation for the rear flue model;Easy access to magnesium rod for replacement – 1 anode rod;Factory installed brass drawoff;Factory installed brass well for aquastat;Heavy duty glass lined steel tank – Cobalt Porcelain Enamel;Large observation door for efficiency testing;Attractive baked enamel steel jacket;Made in the U.S.A.