Prevent Breathable Assembly - The body of the garment is made from sweat wicking fabric. This helps encourage ventilation and keeps you cool, which is important if you use a vest or harness above this item. | Old School Fit - This style fit is to ensure comfort without being baggy. There are areas where stretch flex material is used to allow for minimal restriction and maximum mobility. The stretch flex material is strategically built into the shoulder and elbow areas.