The NORITZ NR98SV is a residential tankless water heater designed for use with single wall category III stainless steel venting. All NR98 models are built around Commercial Grade Copper heat exchangers that are 25% thicker than competitive models. They are housed in durable stainless steel casings with a polyester coating. What's more, by utilizing a quick connect cable, you can link two NR98 heaters together for increased capacity and redundancy. Ships complete with controller and 6 power cord. IK-WV-200-1-XX-LF valve kit (required for installation) is sold separately.