This 4 x 5.65" Firecrest Ultra Cine Superslim IRND Filter from Formatt Hitech is a glass filter that is a mere 2mm thick so that it weighs less and can easily be incorporated into cinema camera setups on drones and gimbals or simply to just provide you with a lighter option. At 2mm thick it weighs about half the weight of standard thickness 4mm ND filters.
Using an optional Formatt Hitech 2mm filter tray, the filter can be used with most ARRI, Bright Tangerine, Chroziel, and Wooden Camera matte boxes. No tray is required for matte boxes with clamp-style filter holders such as the Bright Tangerine Misfit Atom. This filter is a good complement to ultra-lightweight matte boxes like the Misfit Atom. The filter is also compatible with the Formatt Hitech Firecrest 100mm MKII holder, which allows you to adapt it to threaded photography and cinema lenses from 86mm to 37mm screw-in sizes.