Description: This kind of O2 battery repair actually has a built-in micro catalytic converter, which helps to get rid of the annoying engine check that appears after replacing the exhaust gas or removing the catalytic converter (sometimes even when installing a high-flow catalytic converter) light. Only when they do not work, you can try to expand, this is the built-in real mini Catalyst. This kind of O2 battery device with a mini cat will deceive your ECU into thinking that a stock catalytic converter is still installed. When you remove the catalytic converter, the rear oxygen sensor will see a higher temperature and a greater flow of unburned fuel. Therefore, this will trigger the inspection of the engine lights (Cell, SES, DTC), usually the error code is P0420 (catalyst system efficiency is lower than threshold group 1) and/or P0430 P0420-catalyst system efficiency is lower than threshold group 2). For off-road use only. Specifications: Product name: sensor filter joint Material: Stainless steel Size: 46.5mm long (1.83Inch) Color: as shown in the figure Package Included:1x sensor filter joint Notes: 1. Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you 2. Please allow 0.1-2cm measuring deviation due to manual measurement.