Denso spark plugs are a Japanese brand. Speaking of Denso spark plugs, we should introduce Denso. Denso is Japan’s number one auto parts OEM manufacturer and is a supporting manufacturer of Toyota. The famous HKS modified spark plugs They are manufactured by Denso, and Denso spark plugs are also specially formulated for F1 racing cars. Denso's 0.4 spark plug's iridium technology is the only and thinnest in the world, and the U-shaped groove is also Denso's patent.