Factor 1 Eco Mens Long Sleeve Base Layer Tops provide excellent insulation without the bulk that comes with wearing mid layers. 

Knitted from a blend of antibacterial bamboo, super soft merino wool, recycled polyester and stretchy elastane yarns, these base layer tops are not only kinder for the environment, but are also some of the warmest we have ever manufactured.

Nearly twice the weight of our popular Factor 1 Plus range, these base layers act like a second skin with their three way stretch. The lightly brushed inner face not only provides greater heat retention, but also a softer handle when worn next to the skin. 

The ergonomic design is based on our award winning Factor 2 mid layers, with flat seams to eliminate seam rub, and contoured body panels to provide a tailored fit. The low profile round neck is constructed to stretch when placed over your head, whilst the set-in sleeves and long body lengths help to improve wicking and thermal efficiency. 

These Sub Zero Eco tops are ideal for prolonged cold weather environments and cross over in to anything from skiing through to hiking and camping.  They can be worn on their own or used in combination with the Sub Zero Factor 2 thermal mid layer range for extra warmth in extreme conditions.