Formatt Hitech FCU4X5ND0.9 Firecrest Ultra IRND 4x5.65 Neutral Density Filter 0.9 (3 Stop). Firecrest ND is a revolutionary new type of ND filter from Formatt-Hitech. Rather than dyed resin, Firecrest is a rare earth mineral coating used to create hyper neutral NDs. The filters are made from 4mm thick Schott Superwite glass, and the multicoating is bonded in the middle to increase scratch resistance. Firecrest Filters are neutral across all spectrums, including UV, visible, and infrared. Firecrest Ultra filters are the first bonded, then lapped and polished filters available in the photographic market. They have a lower reflectivity than earlier filters and a clarity and sharpness, even at longer focal lengths, unprecedented in photo filters, whilst still delivering the neutrality that made Firecrest so popular.