NGK's patented NHTC (New High Temperature Ceramic) glow plugs were developed for OEM diesel engine manufacturers to comply with ever - stricter emissions standards. Compared to metal glow plugs, NHTC glow plugs have a more robust, fully ceramic heating element which is encased in a ceramic insulator. NGK NHTC glow plugs reach operating temp of 1,000 degrees C in less than 2 seconds and can after - glow for more than 10 minutes at temps of up to 1,350 degrees C. Silicon nitrate ceramic material, combined with optimized shape and joining process provide superior thermal shock and vibration resistance, ensuring stable engine starts. Fine ceramic heater provides durability in high - temperature conditions, improves combustion and reduces emissions.