Lang Basic Exhaust Back Pressure Kit enables technician to test exhaust back pressure through the oxygen sensor. The Lang oxygen sensor adapter includes M12 and M18 thread, and the special 2 1/4” gauge has two multi-colored bands – idle and 2500 RPM, with pressures shown in PSI and bar. The Lang kit includes a boot for protection, and a 6′ hose, enough length for the technician to test from the drivers seat.