Mango Casuals cowl neck sleeveless knee length dress or tunic in size XS. I believe this could also be worn as a tunic because of the high slits on both sides, but the label indicates it is a dress, just in case!

Measurements:
Length: 35 inches
Armpit to armpit: 14 inches

Material tag is missing.
Measurements are not doubled and are measured with the item laying flat.
Measurements are approximate, not exact. BinJ