I like that little satchel. It would be perfect for me if I could hang my coffee thermos off it somewhere. What are the rough dimensions?
Not sure how big your thermos might be, but I had to look it up to see how big it really is. I’ve always considered it a small pack, but I’ve been amazed several times in the last 12yrs how much it can hold. Which is what we want, right? A pack that carries as if it were smaller than it really is? I’m glad you asked, because I have never tested it out for gross volume. I have three of them, I use one for hiking with a DSLR and lenses, one for a hunting and shooting pack, and used the 3rd for my daddy diaper bag when my son was younger - since then, my wife has appropriated it. I bought my first one on a whim years ago, but we find them exceptionally handy. Small enough to haul without being annoying, but big enough to haul everything we need when we don’t need the kitchen sink.
Here are the specs as listed on the site - it’s a 6L pack, main compartment is 8 3/4” x 7 3/4” x 4”, which looks small on the outside, but is able to accommodate a surprising amount of stuff inside. The side pockets are listed as 7 3/4” tall x 4” wide x 1.5” thick (out from the side), but I can tell you, that is the “zipped closed” dimension - see photo below.
To put some context to those numbers, I had my wife grab mine and throw some stuff inside for reference.
With the side bottle pockets zipped, a 20oz Gatorade fits comfortably - I zip them shut then hook the connected zipper pull over the top of the bottle to lock them closed. It’s never come open without it locked, but it’s a handy trick. With the zippers open, as pictured below, a 1L Nalgene bottle will fit in either side. I add a bungee to corral the top of the bottle and ensure they don’t slip out, but they fit very easily into the expanded bottle pockets.
Pictured in the main compartment is an 8lb jug of Varget. It dropped in without wedging - you can see the slack around the sides, and the nalgenes do bulge just a little into the rectangular space of the main compartment, so something larger than an 8lb powder jug would fit if you had smaller water bottles in the side. The lid WILL flip closed on that 8lb powder jug, and clasp. You can fit taller stuff in the main compartment than I really want to carry in a pack like this, as there’s about 2-3” of extra strap on the buckle from where I normally use it (see bottom middle of the pack in the pic in my post above for the buckle and expandable strap).
If you have a tall skinny steel Stanley Thermos like my wife uses (and dad, and granddad), it’d be a bit too tall for the bottle pockets to secure, but it would fit. Throw a bungee around the top and anchor it to the bag, or use a shorter thermos, and you’d be fine. I just wouldn’t expect it to stand up when you set the bag down. Any thermos about the size of a Nalgene bottle would be an easy fit, and more appropriately sized for the bag.