Mrs. Crosby Train Case is a fingering-weight, 3-ply, 55% superwash Merino wool / 30% Outlast rayon / 15% nylon yarn with 425 yards per 100 gram skein. Train Case is a perfect sock yarn, soft and beautifully hand dyed in Mrs. Crosby's signature saturate tonal semisolids and varigated coloways. The blend of superwash Merino wool, nylon, and Outlast, a rayon fiber technology that continuously interacts with a body's microclimate to moderate temperature from being too hot or too cold is machine washable.Ê