Rip-stop fabric for longer play. This 2.5 layer is made to resist tough weather and tough treatment. Then when the sun comes out, just stow it in the chest pocket and forget all about it.
The fabric floats as if weightless. The minimalist design excludes any surplus trimmings. Waist, wrist and hood adjustment is there with an effective elasticated fit. Keeping it simple.
Designed for extra ventilation where you need it: in the back, the sticky zone.