Star Products STATU24APB Three Way Exhaust Back Pressure Kit Allows quicker and more accurate testing of exhaust blockages in catalytic converters, mufflers, etc. The 2-1/4" special gauge has two multicolored bands for measuring at Idle and 2500 RPM; the scale ranges are in PSI and BAR Furnished with rubber boot to protect gauge Hose is 6', enough length for the Technician to test from the driver's seat