The Nike Sphere thermal technology offers cutting-edge insulation and protection from the winter chill.  Unlike traditional heavy down jackets, which tend to look puffy and cling to the skin, the Sphere jackets manufactured by Nike are said to leave a small layer between the jacket fabric and the skin.  This allows you to generate your own body heat and retain it.

Sphere technology actually prevents the heat that you radiate from escaping the confines of the fabric.  Thus, you develop your own personal several millimeter atmosphere.  In this way, wearers can get more breathability than with traditional clingy, downey jackets.  Most Nike Spheres products are far lighter than their bulky counterparts.

Although the Sphere technology is in its nascence, consumer and industry reviews of Sphere products have by and large been extremely positive.  Most Nike jackets do not ostentatiously front for their brand--a respectable but modest swoosh adorns Nike Sphere jackets

Sphere products are also said to provide ventilation to allow moisture wicking and to prevent sweat buildup and condensation (which can cool you down if you are working out outside in the winter).  All told, the Sphere concept is generally regarded as simple, unassuming, and generally successful at providing a neat pocket of thermal installation heated by the wearer. 

Although the Sphere concept bucks the conventional wisdom that you should dress in layers to stay warm in cold weather, it retains thermal energy based on the same basic principles.  Sphere jackets and other Sphere gear are also remarkably cozy, according to reviewers.