Swift System (A) module Compatible with all (B) modules like bridge rings, drop-in filter rack, and magnetic VND filter ALL sizes fit 67-82mm Magnetic Bridge Ring (B) modules can magnetically be attached to work with (C) modules like a square filter holder, matte box, or hood All RevoRing products are made using Architectural grade Aluminum, keeping it lightweight and tough Built with magnetic thread which works flawlessly with H & Y magnetic clip-on filters