Formatt-Hitech offers a variety of filter holder systems for different applications:
85mm Nylon holder is a value priced holder with three fixed slots.
85mm Aluminum holder is modular and an excellent choice for DSLR hobbyists
100mm Aluminum holder is the most popular holder system for DSLR photographers and HDSLR cinematographers.
165mm Lucroit system is for wide angle lenses such as the Nikon 14-24