Thermal fabric isn't typically associated with quality, as it is typically a layer, worn under other garments to keep the wearer warm in inclement conditions. Noah’s Heavyweight Thermal elevate this fabric to a premium level. Instead of a simple basket pattern, its two layers are knit separately, then braided into a network of elongated hexagons. This creates both sizeable air pockets to trap body heat, and a structure that allows the two sides to gently pull in opposite directions, meaning the fabric reliably returns to its original shape after being stretched. This makes it perfect for maintaining warmth during chilly winter runs.