3 layers, each with its own function.
Base layer
✓ Function: moist regulating and insulating
✓ Material: technical underwear, mainly made of synthetic fabrics or merino wool
Middle layer
✓ Function: insulating
✓ Material: fleece, wool or down
Outer layer
✓ Function: 100% windproof and waterproof
✓Material: softshell or hardshell