Special additive for flexing of 2K systems i.e. 2K Primers, 2K Paints or 2K Clear coats. Flexing all the above is absolutely necessary for painting elastic parts of the car (bumpers, spoilers etc). Add 5% by volume to the 2K Primers and 10-15% by volume to 2K Paints and Clear coats, after the hardener is added according to the instructions of the 2K product.