It is basically a clear basecoat. It has a few uses. Custom guys use it to mix with their kandies or flakes as a carrier. A normal shop would use it as a wet bed like I mentioned to cover sand scratches on heavy metallics so the flake doesn`t show on the blend area. It lets the flake lay down where you can`t see the blend. You can also use it for the blend itself by doing your color to cover the repair and then mix it 1:1 with your base to thin it out and make it more transparent. Custom guys also use it to cover kandy after it has been sprayed because if you apply an activated clearcoat on top of it directly it can bleed into the clear and ruin the art work. It acts as a barrier coat.