I know. When you tried to remove the nut for your O2 sensor, it was seized. Or it stripped the threads coming off. Or it pulled the stud out of the pipe/manifold. Been there.
A combination of high exhaust temps, road grime, water splashing up on it, rust and age have taken a toll on yours. Have this kit handy when you replace your O2 sensor. Otherwise, suffer the shame.
4 piece OE kit includes the proper studs to hold up to the heat and proper lock nuts to keep the heat from loosening up your goodies. No one wants loose goodies.