It means:
We have redesigned the trolley from scratch, even its internal structure, to provide maximum stability. 
The bottom consists of a single plastic part that protects all around – 360° the corners, which are the most sensitive point of the trolley. The wheels have a significantly larger diameter for greater durability and better rolling. The handle is ergonomic and the reinforced aluminum uprights can be adjusted to TWO heights. 
INSTRUCTIONS FOR THE CONVERSION OF A TROLLEY BAG TO A BACKPACK.
(1) Push the button and fully lower the handle mechanism.
(2) Release the straps from the storage case.
(3) Snap them to the clips on the bottom sides of the trolley.
(4) Unfold the rain cover and cover the bottom of the bag.
(5) Wear the bag on your back and adjust the straps.
CAUTION:
For faster conversion of the bag into a trolley, you can put the straps into the back case without unlocking the clips.
Make sure that the straps and the wheel cover are fully retracted because they can be damaged.
Impacting the backpack on the stairs can cause significant damage. We recommend holding it from the fixed handle or wearing it as a backpack.
