This is an excerpt from the New Equipment Training DVD we out together to educate users about the Protective Combat Uniform (PCU) for which I was the subject matter expert hired by the DoD to help design the system.

If asking a piece of gear or system to address all possibilities, concessions must be made. "Waterproof/ breathable" shells (herein described as "hard shells") compromise in favor of impermeability, meaning they are more waterproof than breathable. This is appropriate for situations where the user is more often static than mobile, or situations where there is little difference in the user's physiology whether moving (infantry-style movement in secure area) or static (standing watch on a perimeter, riding on the outside of a vehicle). However, today's SOCOM operator is active and mobile. Moving faster, he produces more heat and moisture or initiates operations already saturated (OTB). The difference between his physiology while moving and static is too great for a clothing system based on compromise to bridge.