Because the best time to wear a striped sweater is all the tiiiiiiime. And it's much easier to wear a striped sweater all the tiiiiime when you have more than one. That's why there's two colors available.
This item is meant to have a looser fit than typical sweaters.
Sizing *Please be sure to check your measurements with the size chart
ONE SIZE: BUST - 106 CM, LENGTH - 66 CM, SLEEVE - 55 CM