The Polaris has a high grade 444 stainless steel tank with brass connections for years of dependable, trouble-free service - no anode required. 10-year limited Tank Warranty, 10-year Limited Parts warranty for Residential applications Condensing Design - Helical internal heat exchanger keeps hot combustion gases in the tank longer to transfer more heat into the water Whisper Quiet Operation - Ultra quiet blower and burner minimize noise Power Direct Vent Design – Vents with PVC, CPVC or Polypropylene (solid core only) though a sidewall or roof (Price subject to change without notice. Check stock before order)