The problem I have had with most in drum thermos is that you really need to keep them clean. Like with steel wool. Apparently the patina that gets on the needle doesn't conduct heat as well or something ?? So, they work great the first 4 cooks and then start to wander until you clean them.
Large Big Green Egg, Cold smokehouse,
UDS with hinged lid, Santa Maria pit
26.75" Weber OTG, Weber Performer, WGA
MAK One Star General Pellet Pooper
Hasty Bake Gourmet
Custom wooden handles for BBQ's made by Marty Leach (oh, that's me)