The Extreme White/Primer Superior Grade Aerosol Paint is used for exterior applications when you want an ultimate bright finish. Using the Extreme White/Primer Superior Grade Aerosol Paint primer gives the Spaz Stix paint you're using a very bright backer to make the colors pop. Your yellows will be more yellow, your blues will be more blue, and any bright color application will be more dramatic when finished. Unlike traditional grey primers, which can darken the hues making your yellows dark with a tint of green or grey and your blues darker with a tint of purple or grey, the white primer will allow the true color you want to STAND OUT. If your wanting a bright vibrant finish on your project you should definitely start here. For use on exterior applications only.