The 67mm Peter McKinnon Signature Edition Variable ND 1.8 to 2.7 Filter from PolarPro is designed for lenses with 67mm front filter threads and provides an exposure reduction of 6 to 9 stops. The 1.8 to 2.7 density creates a darkening of the entire image, allowing a wider aperture or slower shutter speed than usually possible. The degree of density is easily controlled by rotating the front filter ring, helping to predetermine the additional exposure length required. By slowing the exposure time, you convey movement or increase the blur. By increasing the aperture, the image depth of field can be more easily controlled. For easier, repeatable control over density settings, the front ring features a numbered scale of the stop values, and it also features haptic feedback to feel a click when reaching a number without the need to look at the ring. The ring features side knurling for a secure grip and to further enable fast and precise positioning, and it is designed to prevent any rotation beyond the stop values etched on it. This filter is constructed from quartz glass for enhanced durability. To prevent internal ghosting and reflections, 16 layers of antireflective coatings offer scratch protection to the filter substrate while promoting clarity and color fidelity. The coatings also provide improved beading when in contact with water or oil, allowing for more efficient cleaning. The quartz optics are set within an aluminum alloy filter ring assembly for lightweight durability. The unique Defender 360 hybrid case/cover is included for storage and transport and acts as both a front cap when the filter is in place on a lens and as a rigid dustproof and waterproof storage case by adding the rear cover when the filter is not in use.