In addition to the basecoat, the company provided the primer and prep materials, all seen here. LE3404S is a medium-gray urethane primer filler, meaning it’s intended to be sprayed on the car in several layers, then mostly sanded off, leaving a flat, wave-free surface for the paint. The paint is then mixed with an activator/reducer in a 4:1 ratio. Your paintjob will look best if you match the primer color to the basecoat. DuPont assigns each of its basecoats a ValueShade number and recommends using a primer of the same number. Other paint manufacturers have similar systems.