From Moondrake Co. website:
437 yard / 100 gram
90% Superwash Merino 10% Nylon 2-ply Yarn. This yarn is spun intentionally to achieve an irregular shape, in terms of length and diameter, called Slub yarn. Slub yarn refers to yarn that has been purposely spun with slubs (thicker sections along the yarn). This texture is intentionally created to give fabric more personality. It is highly twisted and quite crinkly, very fun to work with.