FRANK LYMAN Open Cardigan Cover Up 3/4 Sleeve Stretchy Jersey Knit Size 12?

This pretty FRANK LYMAN open cardigan is in very nice pre-owned condition!   Material tag is missing.  Most likely a blend of polyester with a bit of spandex.   Size tag is missing therefor, please consider the following measurements before purchasing.  Thank you! Measurements (taken while laying flat): Bust (armpit to armpit) - 20"                      Shoulder (seam to seam) - 16"                 Sleeve (shoulder seam to end of cuff) - 17.5"    Length (neck seam to end of back hem) - 29"