Ace Race Parts 74007 M12 x 1.25 O2 Sensor Bung Plug - 6AL4V Grade 5 TitaniumAce Race Parts 74007 M12 x 1. 25 O2 Sensor Bung Plug 6AL4V Grade 5 Titanium 6AL4V GRADE 5 TITANIUM O2 SENSOR BUNG PLUG M12 X 1. 25 THREAD The Ace Race Parts brand of metric Oxygen (O2) Sensor Bung Plugs 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.