TWENTY Montreal Mackay Rib Racerback Dress in Black. - size XS (also in L) TWENTY Montreal Mackay Rib Racerback Dress in Black. - size XS (also in L) 92% viscose 8% spandex. Made in Canada. Machine wash. Unlined. Pull-on styling. Racerback styling. Light ribbed jersey fabric. TMON-WD1. RQ5S-088. Twenty has transformed a fashion essential by giving the classic knit tee a luxurious and modern take. Crafted from amazing fabric, twenty creates super soft tees, knit dresses, bodycon skirts, and cozy sweatpants that will quickly become everyday staples in your wardrobe.