We needed to add a couple of extra bowls to our kitchen kit last summer so I decided to try out the GSI Ultralight Nesting Bowl and Mug.
These guys weigh in at 122g (4.3oz) and hold 590ml each. The insulated mug nests inside the bowl. It's a snug fit so there's no rattling around. They can also be used as replacements for the GSI Dualist Cookset.
Overall I found that they worked really well for keeping the kids' oatmeal warm on cold mornings. The lid fits tightly, so there's no worry about spills. My favourite thing about these was something that I didn't anticipate when I bought them - they are fantastic for rehydrating food.
They are just the right size for salsa, applesauce, pizza sauce, etc. I put our dehydrated food in them, added boiling water, gave it a stir, popped on the lid and insulator, wrapped them in a pot cozy, and that was it. 15-20 minutes later the food was rehydrated and still warm. For added insulation I doubled up the bowls and wrapped them in a pot cozy.
These guys have definitely earned themselves a spot in my minimalist kitchen kit.
Pros: The lid was nice and tight and stayed in place. I worried that the insulator might be tough to clean, but it washed up easily and dried quickly. The insulator does a good job of keeping in the heat and the food didn't end up tasting like plastic.
Cons: I couldn't come up with any cons, other than the fact that the “mug” isn’t really a mug. It’s a bowl with a lid on it. Personally, I like drinking my coffee from a real mug so I didn't use it as a "mug", but with the tight fitting lid it would certainly do if you were slashing gear.
I got mine at Adventure Guide, but they are also available at MEC, REI, etc.