The OEMTOOLS Exhaust Back Pressure Gauge, No. 37263, allows users to test exhaust back pressure through oxygen sensor, showing both psi and bar. The oxygen sensor adapter is M12 and M18 thread and features a 2-1/2" easy-to-read gauge. The gauge has two multi-colored bands to test idle and 2,500 rpm. The 6' hose allows for testing from the driver’s seat.