The Chunky Rib Heat Holders 3.4 Tog Hat is exceptionally thermally effective, with a HeatWeaver plush insulating liner that holds heat in. Its soft fur-like lining feels great against your skin and efficiently uses heat that naturally rises from your head to keep you warmer for longer.Outer: 53% Polyester 47% Acrylic, Lining: 100% PolyesterHeatWeaver plush liningStretchable rib constructionAdvanced insulating yarnSize: Approximately 8.5\" High, 9.25\" WideMachine washable at 40°