The Stretch Fibre is a single layer soft cover. It is perfect in most conditions except damp areas. The stretch fibre cannot be 100% dust proof as you stretch the fabric you open the weave every time you pull the cover to stretch it over the car, they are approximately 90% dust proof and you would only notice any dust after a period of time.
Do not confuse this stretch fiber cover with others, it is more expensive for a reason, this is a 120g fabric and the cheaper options are much thinner offering even less dust protection. This is the heaviest fabric we can find to give flexability and dust protection.
This material is great for covering cars with spoilers or irregular shapes as it will cling to any shape.