Made from 50% merino wool and 50% acrylic with a polyester lining, the Windstopper 1/4 Zip Sweater is designed to offer maximum comfort and freedom of movement during play. The high quality design with Opti-Therm technology provides an extra layer of thermal comfort. Featuring a windproof lining, the garment blocks out wind to the body and provides better thermal insulation on cooler days.