Filler Prep Adhesion Promoter helps filler stick to plastic. Its necessary when applying fillers to TPO and polypropylene parts, like most late model bumper covers. Filler Prep allows the filler to get a good "bite" on the plastic and eliminates the peeling problems common on many automotive plastics. Each can has a brush on the lid and is ready to be used as soon as you open the can. This 4 fl. oz. (118 ml) can contains a built-in duaber to apply the adhesion promoter.