Michigan Motorsports LS1 02 Oxygen Sensor Header Extension Harness 24" 4-pin, O2 Extender - Fits Camaro Firebird Pontiac Chevy This is the Black Square 4-pin plug used on most LS applications These oxygen sensor extensions will make for an easy installation and will avoid the problems of faulty O2 sensor readings that are common with cutting and splicing. This package contains a pair of oxygen sensors.