Sewn on 38th Street in NYC by Flora Huang and her master sewers, with hand woven khadi fabric, this shirt is built to be worn and loved for many years to come. The fabrics are a mid weight and breathable for steamy Summer days. This top is also lovely worn over a dress if you'd like a little something to cover your arms.
There isn't a tremendous difference between the two sizes. I'd say that the size 1 is great for size XS - M and the Size 2 is great for Size L - 2XL.