The Icebreaker Women's Siren Bikini underwear bottoms are so soft and cozy you won't even realize you're wearing your underwear. The Siren Bikini features our corespun merino wool blend for added strength and durability, while retaining next-to-skin softness. Features: 150 Ultralight 83% Merino Wool, 12% Nylon, 5% LYCRA(R) corespun Medium = 32 g / 1.13 oz Bulk free comfort at waist and leg opening, side seams moved forward for additional comfort, corespun fabric for added durability