Formatt-Hitech filters are made from durable 2mm thick Schott Superwhite glass that is treated with a rare earth metal coating process (it is applied directly to the glass through an electrolyte process). And unlike the tradition resin dye, Firecrest glass filters are hyper-neutral across the visible light and UV spectrums, and also remove more IR contamination than any other filter, allowing you to capture high-quality long exposure photos.