A gas tankless water heater is sized by the flow it must deliver at the temperature rise your inlet water demands: read the stated maximum GPM, the BTU/h input, the fuel (natural gas or propane) and whether the unit is listed for indoor or outdoor mounting. Gas supply, venting and combustion air are decided by a licensed plumber or gas installer under your local code, not by a listing.
Exact listing: Natural Gas Tankless Water Heater, Outdoor Installation, Up to 5.3 GPM 130000 BTU On Demand Residential Natural Gas Instant Hot Water Heater Outdoor with Remote Controller, 110V, CSA Certificated,Gray
Listing identifier: B0DKMD4HZD. View listing source.
Title identifies the seller's listing; it is not an independent performance test. Check the selected configuration, current price and seller on Amazon.