Built with 25 years of women’s-specific design, the Merrell Siren 4 Thermo is crafted to support the unique shape of female feet on even the longest winter hikes. With 200g of Primaloft® Gold Eco insulation and advanced SOLARCORE® technology—originally engineered for NASA—your feet stay warm without added bulk.
A new medial zipper, inspired by customer feedback, makes on/off effortless, while Merrell’s waterproof full-grain leather upper and breathable membrane ensure dry comfort in wet, snowy conditions. Underfoot, Vibram® IceTrek delivers reliable grip on ice and snow, while the addition of Vibram® traction lugs enhances stability and sheds debris step after step.
Best for: Winter hiking
Insulation: 200g Primaloft® Gold Eco + SOLARCORE® Aerogel insole for superior warmth and flexibility
Waterproofing: Waterproof leather upper with moisture-wicking membrane
Traction: Vibram® IceTrek outsole with traction lugs for secure footing on icy, uneven terrain