Intraknit Thermal Merino Base Layer 3/4 Bottom - Men'sReady for winter's swirling gusts and dipping mercury, Smartwool's men's Intraknit Thermal Merino Base Layer 3 4 Bottoms will help you stay warm, active, and protected for all of your backcountry adventures. These Intraknit bottom's feature Merino Sport yarn, a fabric created by combining the comfort and durability of Merino wool with the strength and durability of polyester, serving up insulation, motion mirroring mobility, and plenty of ventilation.