100x100mm filter reduces light by 13 stops. Fire crest technology is hyper neutral across all spectrums, including UV, visible, and infrared. Made from 2mm Schott Superwite glass, the finest optical glass available. Fits the Formatt-Hitech 100mm holder system, so a single filter is usable on multiple lenses. Made in the UK on the most advanced computer-controlled manufacturing equipment in the industry.