Merino wool fibres are naturally fine and long creating a wool garment that is soft, smooth and extremely warm. Merino fibres are naturally 'crimped' which gives the finished garment an inherent elasticity that won't wear out. To ensure durability and optimum performance Brynje added polyester filaments to the Merino wool yarn. The Merino blend is 70 % Merino wool and 30 % polyester. The result are garments that are soft, very durable and able to withstand years of adventures. Brynje Classic Merino wool underwear is designed to complement the Super Thermo net base layer. While the Super Thermo net creates a regulated warm cushion of air next to the skin the Classic Merino provides a mid-layer that will transport excess moisture away from the body and provide excellent insulation even when it is damp or wet. Note: Classic garments are designed with a functional 'body contour fit'. If you will be wearing these as a mid layer we recommend you order one size larger than normal.