I've got a tell-tru BQ300 with the 3-inch dial and 4-inch stem.
I really like it a lot for the following reasons:
<UL TYPE=SQUARE><LI>It's big enough such that I can read it "ballpark" from my kitchen window.
<LI>The long stem reads the temp inside the lid, but not right AT the lid (closer to grate temp)
<LI>It has held-up to being outside in Rain and Snow
<LI>After over 4 years, it's still clear and solid
[/list]Never checked its accuracy - but, I figure that if it's within 25 or so degrees, it's close enough for BBQ use. (I don't lose sleep over 25, sometimes even 50 degrees.)