I like the flattening agent because you can tweak it to the exact look you want. If you do use it make some test panels and write down how much flattener you used so that if you have to repair it will match. About a month after finishing the Chevy it was hit in the quarter panel. We knew how much to use so matching it was easy. I used Omni (PPG Brand) M148 flattener, P sheet shows 51oz per gallon for flat 45oz per gallon eggshell and 42oz per gallon semi gloss. Clear was Omni MC-161. Not hard to do but not as easy as matte clear.MARTINSR said:"Matte" clear is what it usually called. It is the ONLY way to go in my opinion. Adding flattener always opens a can of worms. Matte clear is a no brainer.