US Chemical 2K Urethane Sealer Activator is activator is ready to mix with 2K urethane primer sealer (sold separately). When mixed, the primer builds fast, dries fast, and sands fast. It's ideal for adhesion to bare substrates, sanded OE finishes, and body fillers to cover minor imperfections, and is made to ensure smooth, clean, and even paint application with fantastic results. Whatever car paint project you are about to undertake, choose to use superior prep work, refinishing and paint products from US Chemical.