Two-wheel luggage is most commonly referred to as "Rollaboard" or "Upright" luggage. The term "Rollaboard" was actually coined by Travelpro, the company founded by a pilot who invented the first vertical wheeled suitcase with a retractable handle in the late 1980s. These bags are designed to be pulled behind you at an angle, utilizing two fixed wheels that only move forward and backward. Unlike four-wheel "Spinner" luggage, which sits flat on all four wheels and can move in any direction, two-wheel bags have wheels that are usually recessed into the frame. This design makes them more durable and better at navigating uneven surfaces like cobblestones, thick carpets, or curbs, as the wheels are protected from impact. Additionally, because the wheels are recessed, two-wheel bags typically offer slightly more internal packing space compared to four-wheel bags of the same exterior dimensions, as the wheels don't take up as much of the height allowance. Frequent flyers often prefer two-wheelers for their stability and ability to handle the "wear and tear" of heavy travel better than the more delicate caster wheels found on spinners.