A brief introduction to luggage

Early suitcases were made of wood or other heavy materials, but with the popularity of air travel, the materials used for suitcases tended to be lighter, harder plastic or cloth. Most models also come with built-in wheels, which can be easily pulled by a lever. After 2010, there were also suitcases with four wheels, which can rotate 360 degrees and be easily pushed on flat ground.
Luggage can also be divided into hard shell luggage and soft shell luggage according to the outer shell. Hard shell suitcases are more resistant to falls and are suitable for luggage that requires more protection. Soft shell luggage is usually lighter in weight than hard shell luggage, and the material is also more elastic. However, the zipper position of a soft shell suitcase is more likely to burst due to too many items inside.