Hot Chilly's Micro-Elite Zip-T - Men's:  Hot Chillys® Men's MEXT Mountain-Weight Zip-T is one of the warmest body fit base layers that is fleece on the inside and has that 'jersey' look on the outside. It is heavy enough to wear as base layer or as an everyday sportswear second layer. The fabric is smooth and soft outside with plush, ultra-low loft fleece inside; made with moisture transfer fibers that pull moisture away from the body to keep you comfortable in extreme conditions.