I bought sky bags recently when I was travelling to abroad. Since I was travelling for 3 months I need to carry all my cloths and things which I used for my daily activities.
When I went to a shopping mall to buy the bags, they showed me a wide range of bags with different styles and diffrent metal like leather, plastic suitcase bags etc. finally I went for the leather bag which has the capacity of 20 kgs, it has wheels for easy carrying.