Slinky stretchy material.  If you aren't tummy heavy, definitely size down one.  Ash is a 16/17 and in the XL but can wear the large also. 

Details

3/4 Balloon Sleeve

Brand: Sew In Love

Color: Emeral Green Base, Blush, Black, Sage, Cream

Sizing

S (2-6) | M (8-10) | L (12-14) | XL (16-18) | 2X (20-22) | 3X (22-24)

Ashley (Size 16 regular and 40H bust) wears the size XL 

Fabric Fit & Feel

94% Poly 6% Spandex

Slinky Stretchy no wrinkles

Relaxed fit with room in the tummy (Taco friendly :-)

Measurements (approximate and taken while laying flat)

Length from shoulder to bottom seam: Medium 28 Inches | 2X 30 Inches

Bust width: Medium 44 Inches | 2X 52 Inches