Engel 60% Organic Merino Wool/30% Silk bonnet matches Engel's lovely pink or mint striped onesies. A baby cap gives gentle protection to baby's crown area, still not completely closed. Compared to the rest of the body, the head of a baby is relatively large and the heat loss through the head is significant. The baby's head stays warm under the cap without feeling hot. Wash by hand or machine washable on gentle cycle in warm water.