Another key element to think about when buying a fleece is breathability. When active your bodied temperature rises, and sweat is produced to cool ourselves down. Having a breathable layer means that this perspiration is wicked away from the body keeping you dry and warm.
Breathability, as already mentioned has a direct correlation with the weight of the fleece, a lighter fleece will be more breathable, however, this does not mean that a heavyweight fleece cannot be breathable. As of late, companies have started to use a variation of thicknesses on a single jacket, utilising a heavyweight fleece for a high degree of warmth and a lighter weight fleece, in key areas to maximise breathability.
Another method to maximise breathability is variability in fabric thickness which comes in a more micro level. Often referred to as “grid” style, the inside of the fleece appears to be checkered with thin channels in between thicker squares. These thin channels provide a small gap between the material and the wearers skin which allows sweat to evaporate naturally.