Earl’s O2 Sensor Weld Fittings are a fast, easy way to add a sensor when you upgrade to EFI or add a wideband air/fuel gauge for tuning carbureted applications. Available in steel or stainless steel to match countless exhaust systems, they feature 18mm x 1.5 threads and are compatible with virtually all OE and aftermarket O2 sensors, including GM, Ford, Chrysler, and most imports. They even come with a recessed step that makes it easy to weld the fitting in place. For detailed product information on steel fittings, click here. For stainless steel, click here.