A bralette for C or smaller cup sizes made of Merino wool (knit blend of 81% extra fine Merino wool, 12% nylon, and 7% Spandex). Branwyn sources its merino wool from ZQ New Zealand and the yarn is engineered and spun by Sudwolle Group in Europe. From the brand's website: "Our ZQ, OEKO-TEX, and Responsible Wool Standard certified Merino is also regenerative and sustainable. (which also means it is free of BPA, BHP, and toxic forever chemicals)" making it a great alternative to sports bras typically made of polyester. Coming from a pet and smoke-free home.