- Solid Black – Heavyweight Merino Wool Hat Loose Fit. Comfortable and warm hat made of natural fibers. 100% Merino wool hat designed for protection in extreme cold conditions during low-medium intensity outdoor activities such as trekking, hiking and climbing. Winter hat designed with advanced insulation properties and loose style. Comfortable hat made of natural fibers. 100% Merino wool hat designed for protection in extreme cold conditions during low-medium intensity outdoor activities such as trekking, hiking and climbing. Design: Loose, Solid. Size: One Size. Designed for adults.