The tanks come with a 20-year warranty, longer than any other metal-lined tank that we know of. Thanks to the stainless liner, they weigh about half as much as traditional steel-lined heaters (187 lbs. empty for the larger model). The liner is encased in 2” of CFC- and HCFC-free polyurethane insulation, and comes in sizes from 60 to 119 gallons. And of course, the stainless is almost completely recyclable.