My go-to brow filling product is Youngblood Brow Artiste kit (I ignore the flimsy tools and just use the powders). However, the palette is too big and inconvenient for travel, so I went looking for something smaller that doesn't take up important space in my train case. Anastasia Brow Powder Duo fit the bill: it's the size of an average single eye shadow.
I had a bit of a hard time at Sephora (yes, I actually set foot at the store) deciding between Medium Brown and Dark Brown, but ended up deciding on the latter as the Medium Brown looked a bit too gray on me. Dark Brown might be a tad warmer than I would have preferred, but I've figured out the correct ratio between the two shades in the compact (a cool taupish tan and a very dark brown). I apply it lightly just where needed and it's all good.
Anastasia Brow Powder Duo is soft and pliable but doesn't crumble all over the place and doesn't require a setting product (my eyebrows are quite full but uneven, hence the need for a little correction). The product stays put all day and doesn't migrate. I still like my Youngblood set a bit more because the colors are a little lighter and a better fit in my opinion, but I'm probably the only one who notices the very minor difference.
Bottom Line: a travel essential.
Anastasia Brow Powder Duo ($22) is available from Sephora, online and in store.