The cokin z pro 145 net 2 black resin filter is available in white and black grades 1 and 2 with 2 having the greater effect the black net filter softens fine details with no change in contrast while the white net filters not only soften details but also lower contrast z pro filters are made of cr39 resin which is a reputable lightweight and unbreakable optical material also used for ophthalmic glasses the z pro series is recommended for focal lengths of 20mm onwards in the 35mm format