Stretch knitwear does not size like woven cloth. Read the measurement, not the letter.
Every piece in this catalogue is cut from a soft-stretch knit. That fabric moves with the body, which is why one letter can cover a wider range than it would in a woven shirt, and why the same letter can feel different in a rib and in a seamless knit. The rule that works: measure yourself, compare against the flat measurement on the partner listing, and let the fabric do the rest.
Take the smaller one in a ribbed or seamless knit: rib recovers, and a rib that is too big loses its shape at the neckline within a few wears. Take the larger one in a woven-feel piece, in anything lined, and in a garment with a built-in bra, where the cup position matters more than the body width. If the piece has a shaping panel, size to the waist rather than to the bust.
Crop lengths in this line sit at or just above the natural waist, so a high-waist bottom meets them without a gap. Regular tank and tee lengths cover the waistband. Dresses are cut to the same block, so a midi that lands mid-calf on a 5'6" frame lands closer to the ankle on a shorter one. The measurement on the listing is taken flat from the shoulder seam.
Cold wash, low or no heat in the dryer, no fabric softener on anything with elastane. Heat is what kills recovery in a stretch knit, and a knit that has lost recovery reads a size larger. Swim pieces get a rinse in cold water after chlorine or salt.
Size charts differ between styles, and stock in a given size changes daily, so the definitive chart is the one on the listing where you place the order. This page explains how to read it; it does not replace it. The catalogue currently runs $9.99 to $49.99 across 159 styles, 5 of which are listed in more than one colour.