Rab womens alpha flux jacket the womens alpha flux jacket is a lightly insulated highly breathable mid or outer layer designed with polartec alpha tm direct technology and stretch fleece for multi season active use the womens alpha flux jackets outer shell is a new super soft breathable and durable woven fabric their thermic lux tm stretch fleece has then been added in strategic areas of the body to allow freedom of movement and to keep bulk and weight down the result is an ide