This Grad Kit contains the most commonly used densities of the Neutral Density filter - 1-3 stops (0.3, 0.6 and 0.9). The ND grads feature a neutral gray effect at the top of the filter that gradually transitions to clear at the centre of the filter. The main function of a graduated ND is to balance the luminosity of the sky to the terrain below. It is the most popular and most versatile grad we make because it’s easy to blend the gradual transition into an undulating horizon. Formatt-Hitech filters are made from the highest quality 1.5mm optical resin.