Designed for photographers looking to shoot long-exposure photography, the Cokin Z-Pro Full ND Kit is comprised of 3 popular graduated ND filters: GND2 filter X121L (1-stop, hard grad); GND4 filter X121M (2-stop, hard grad); & GND8 filter X121S (3-stop, soft grad). These filters reduce the amount of light reaching the sensor, allowing the user to experiment with distance & depth of field.