High marks for the Pucks!
I gave my 'loaf about 2.5 hours @ 225-ish, until the internal temp was 166 (I didn't hear the alarm I set @ 160). Since I can't eat my meatloaf w/o some ketchup on top, I slathered it with the red stuff and set it under the oven broiler for maybe 5 minutes to carmelize the paste a bit.
Wow! Very tasty! I ended up eating about 12 oz of it just standing over the sink!
The Pucks give a very nice smoke flavor and are simple to use. I'll have to look and see how much was left at the end up I went 2 Pucks deep.