Is full-grain buffalo leather better than the leather on cheaper duffels?

Yes. Full-grain buffalo keeps the outer grain intact, so it is stronger and develops a patina. Cheaper duffels often use split or bonded leather, which is weaker and does not age the same way.

Which size should I get for a carry-on?

The 20-inch length is the closest to carry-on dimensions; the 24- and 28-inch versions are larger and better for checked or road-trip luggage. All three are 15 inches high and 11 inches wide.

Does it have a shoulder strap?

Yes. It has a detachable, adjustable shoulder strap and a leather top handle, so you can carry it either way.

Is it good for air travel?

It works as a carry-on in the smaller size, but it has no wheels and is heavy when full. Expect to carry it by the handle or strap through airports.

How do I care for the leather?

Wipe it with a damp cloth, let it dry away from direct heat, and condition the full-grain leather periodically. Keep it out of prolonged rain and store it dry.