ClearSign Technologies develops and sells patented combustion burner technology — branded ClearSign Core — that reduces nitrogen oxide (NOx) emissions from industrial burners while improving energy efficiency. The core value proposition is cost: management estimates that traditional SCR systems run $40M–$60M per heater installation, while ClearSign's burners offer a cheaper, simpler path to the same NOx compliance. Independent testing has also shown roughly 3–5% fuel savings versus conventional ultra-low NOx burners. The technology uses a porous ceramic or metal flame holder to stabilize combustion, producing a shorter, more controlled flame that reduces NOx-forming hot spots. Primary customers are oil refineries, petrochemical plants, and midstream gas processors, concentrated in California and the U.S. Gulf Coast. ClearSign sells through direct relationships and through manufacturing partners, notably Zeeco. Product lines include process burners for refinery heaters, the M-Series for midstream gas processing, flare burners for oil producers, boiler burners, and the ClearSign Eye flame sensor. Revenue is project-based and lumpy, with discrete orders proceeding through engineering, testing, fabrication, and delivery phases. ClearSign is asset-light, relying on Zeeco and California Boiler to fabricate its products. As its installed base grows, spare parts are becoming a recurring, higher-margin revenue stream. ClearSign is expanding its channel through a co-branding agreement with Zeeco and adding heater OEM partners, and is also moving toward supplying larger flare system packages to increase revenue per order.