Use this activator with Uro-Fill Primer Surfacer. Uro-Fill is an acrylic urethane primer surfacer that easily sprays to an ultra smooth texture. It is ideally suited for use over body filler, fiberglass, O.E.M. finishes and small areas of bare steel and treated aluminum. Uro-Fill quickly sands with fine grit sandpaper and provides an excellent base for today's high tech finishes. May be reduced up to 20 percent with acetone. Tintable with some basecoats toners. Offers superior top coat adhesion and color holdout. Applications: A premium quality, two component sandable urethane primer-surfacer used for priming/surfacing auto body repairs prior to topcoat refinishing.