GRID has It's own O2 sensor as well. It cost less than the Racepak unit which I already have. I'm getting ready to put in My GRID with O2 sensor to compare to Racepak but with early Summit ET Brackets canceled due to the virus mess It gives Me more time for getting things installed and ready for electronic warfare to break out in late June, July & August. This is of course right when You don't want to be strapped up in the 104+ F heat of California and Nevada. It's better to have the GRID and a Racepak anyway. More data/graphs to argue about