Claims of windproof, waterproof, and breathable are typically red flags and met with high levels of skepticism. This was our reaction and only after rigorous testing in which the materials demonstrated significantly better breathability than all other softshell materials did we make our final choice. Due diligence was performed in everything from California sun to California hail.  The seams on the inside of this jacket are not taped, instead we chose to focus on breathability and rides in storms that are not categorized by a number. However, if you find yourself out when the weather turns, this jacket will be your best friend. 

Dynamic breathability refers to the ability of a fabric to allow movement of body moisture vapor through it; the process is called diffusion.  Breathability can be increased by air movement through or around the fabric; the process is called convection.  To test for this one must simulate this environment in a lab mimicking real world condition.  The water vapor flux is measured in g/m2/24hours.  Higher numbers mean a fabric is more breathable.  Polartec Neoshell is 100% more breathable than the best waterproof breathable shells on the market in dynamic or active conditions.  Additionally no perceived loss of warmth or windchill is involved within this effect.