Ace Race Parts 74003 M12 x 1.25 O2 Sensor Bung - Coped for 1.500-2.500 OD Tube - 6AL4V Grade 5 TitaniumAce Race Parts 74003 M12 x 1. 25 O2 Sensor Bung Coped for 1. 500" 2. 500" OD Tube 6AL4V Grade 5 Titanium 6AL4V GRADE 5 TITANIUM O2 SENSOR BUNG M12 X 1. 25 THREAD The Ace Race Parts brand of metric Oxygen (O2) Sensor Bungs is precision machined using solid 6AL 4V Grade 5 Titanium bar stock and work with all standard O2 Sensors that use a M12 x 1. 25 thread. This specific O2 sensor bung fitting is coped to fit 1. 500" OD to 2. 500" OD tubing; however,