Utilizing a new nano-technology, multi-coating process that applies 16-layers of anti-reflective (AR) coating to the optical ultra-violet (UV) glass, Hoya created a filter that is sharper and 200% harder than the award-winning HD2 circular polarizer filter. In addition to being scratch and abrasion resistant, this hardened coating is also stain resistant and easy to clean when oil and smudges like fingerprints are introduced to the surface. Hoya selected a premium optical-thin high rate transmission (HRT) polarizing film that passes 2/3rds of a stop more light through the filter for faster, more accurate AF and easier viewing through the viewfinder or LCD screen. Giving photographers shooting in light-critical situations better options when selecting the correct shutter, aperture, and ISO combination. The HD3 Polarizing glass is housed in a two-piece, lightweight, low-profile, aircraft-grade aluminum filter frame. This two-piece design allows the filter to maintain perfect parallel alignment to the sensor plane for maximum sharpness and zero distortion. Knurled edges on both rings allow for easy rotation to achieve the desired polarizing effect and easy attachment and removal from the lens. The low-profile design eliminates the concern for vignetting when used on ultra-wide angle lenses, and the front filter threads accept lens caps and other filters for stacking. Re-Certified Resolution for 100mp+ Cameras Patented Ultra-hard Nano-coating process Superior resolution and sharpness Optical thin HRT Polarizing Film Only 1-stop of light loss Waterproof and stain-resistant top coat 5-year Limited Warranty FILTER PROPERTIES AT A GLANCE Filter Factor: 1-stop Glass Type: Hoya Optical UV Light Transmission: N/A Number of Multi-Coatings: 16 Layers / 8 per side Nano-Coating Technology: Yes Hardened Top Layer: Yes Anti-Static: No Black Rimmed Glass: Yes Frame Construction: Press Fit / Low Profile / Aluminum Front Filter Threads: Yes