This Lochinvar Burner Assembly is a natural gas (NAT) burner with an 18-inch length. The assembly includes a #30 orifice (ORF), which controls the flow of gas into the burner. The Lochinvar Burner Assembly is designed to distribute heat evenly, ensuring efficient combustion and reducing energy waste. It is made from durable materials that can withstand high temperatures and prolonged use, making it a reliable component in any heating system.