1 box = 1 complete staircase with 10 or 11 steps Structure, Steps, Railing (internal side), Handrail
Choice between:
Straight staircase: 10 or 11 straight steps
Staircase with 1 turn: 10 straight steps + 1 landing
Staircase with 2 turns: 9 straight steps + 2 landings
Box measurements may vary