Used to establish the working condition of the catalytic converter and silencer by measuring the relative back pressure of the system. Simply connect into the exhaust system using either of the two oxygen sensor dummy adaptors supplied in the kit. Gauge features a colour-coded scale for easy diagnosis and reads both pressure and vacuum so can be used on other areas of the vehicle allowing testing of low pressure fuel systems or engine vacuum. Supplied with gauge hanging chain to allow hands-free operation. Features & Benefits:Contents: Oxygen Sensor Adaptors; M12 x 1.25, M18 x 1.5mm, Small and Large Brass Cone Adaptors, Plastic Double End Cone, Plastic 'T' Piece, Gauge Hanging Chain.Used to establish the working condition of the catalytic converter and silencer by measuring the relative back pressure of the system.Simply connect into the exhaust system using either of the two oxygen sensor dummy adaptors supplied in the kit.Gauge features a colour-coded scale for easy diag