As it sits right now,I'm on the third therm. The original seemed to keep up with the remote until it hit 275 and then stopped there,the first replacement they sent ran a good 25 degrees lower than the remote and the one I have in there now runs 15 degrees lower. Also the first 2 therms I had both fogged up to the point where you couldn't hardly read them.I'm pretty much convinced that almost all OEM therms in the lids are inaccurate. I am also taking into consideration the fact that lid and grate temps will be different because of location so maybe 15 degrees should be okay as long as this difference remains constant. But I have been wondering myself if maybe Tel-tru makes one that will fit where the new WSM therm is located.
WSM 22.5 - Chargriller pro