Full grain synthetic leather uppers, with breathable mesh. The Polartec® 100 lining is treated with Aegis™, which will keep your feet dry. Heel is made with injected molded TPU, which will increase heel protection. Lace up closure for a secure and adjustable fit. The Bellows Tongue for increased foot security. 7.5 mm Narrow Gauge Webbing. The 4.5 mm Ortholite® Anatomical Footbed, will maximize comfort and support. Merrell Air Cushion Midsole will provide breathability. The Vibram® Siren Song™ outsole, combined with the /TC5+ Rubber, will provide shock absorbency. Comfort Range to -20C.