The Black and White backers are fairly simple products, the white backer is particularly popular as its coverage is very good and for a thin paint it needs very few coats.
The Pre-Prep is a formula created to make it even easier to get perfect results on paint jobs and to help keep that paint where its meant to be.
When sprayed onto the inside of a bodyshell the pre-prep paint can clean away the bodyshells release agent and any greesy fingerprints on there. If sprayed onto the outside of the shell it can remove any static from the lexan which gives a much more natural effect for detail work as static doesnt fight against the spray pulling the particals away. A geniunely helpful tool for creating perfect paintjobs and removing some of those troublesome problems. Only a light spray over the intended area is required meaning this will last you through painting dozens of shells.
Please note: The Aerosol black backers is designed to be used as a black paint or a backer for colour change paints, it is not advised for use on Mirror Chrome, for this purpose a waterbased black would be much safer.