A roller backpack has wheels like luggage, but also full backpack straps that let you carry it on your back when wheels aren't practical — on escalators, rough pavement, or when navigating crowded terminals. Unlike hard-shell luggage, it's made from nylon fabric, opens like a backpack, and typically weighs less. The trade-off is that it won't protect contents as rigidly as a hard shell — but for travellers who move between carry styles throughout a trip, the flexibility is worth it.