I use a dual probe remote thermometer.
One probe in the thickest past of the meat, the other on the grating beside the meat. I dont care about the temps where the factory thermometer is located, I care about the temperature right at my meat.
Remote lets you keep the door to the smoker closed and you never have to open and lose heat resulting in a longer smoke time to get the temps back up.
Google "Dual probe bbq thermometer" and pick one to your likings. None will last a life time, but some of the more expensive ones will outlast others.
I have a BGE one ( i think) thats lasted 2 years. It will be replaced in a few months though because its about burned up.