100% COTTON. To make sure you order the right size, you can measure your neck. If you are 38cm/15″ or less, you can order size I. If you measure 38cm/15″ or more, you can order size II. Necks are actually very much alike, no matter your regular size, weight or waist size. For kids sizes, sizes are according to age. Delivery time approximately 2 weeks after ordering.