Chevrolet Silverado 1500, GMC Sierra 1500, Hummer H2. The product is an NTK Direct Fit Oxygen Sensor with the manufacturer part number 21065. It is designed as an OE quality stock replacement part, ensuring compatibility and performance similar to the original sensor. The sensor is produced by NGK, a reputable brand known for manufacturing high-quality automotive components. This oxygen sensor is designed to provide accurate readings to optimize fuel efficiency and reduce emissions.