Castelli\'s warmest baselayer offering both insulation and breathability. The Flanders Warm base layer was made for the conditions seen in Flanders in February. Or basically any month between September and May. It features a high-loft fleece on the inside that provides warmth to spare, and you\'ll love the softness on your skin. Combine this warm and luxurious SottoZero fabric with the excellent moisture management supplemented by mesh underarm inserts and you have the perfect winter layer for under your Castelli winter jacket. The Flanders fabric is stretchy for a perfect fit and combined with the flat-lock seams fits beautifully under the bibs of our winter tights with no bunching or rubbing. Key Features SottoZero Fleece Multi-denier 100% polyester fabric Flat-lock stitching Mesh armpit inserts Flat hem tucks away into tights Mock turtleneck Sizes men\'s XS-3XL Weight 116g Castelli Comfort range -4 to 10C