There are several options for using polarizers or filters.
1. Keep the cover "open" in front with your filter instead of the Outex front port for water-resistant/above water use (rain, mist, sand, mud, dirt, etc.).
2. We make flat front ports (below 77mm) that offer external threads (77mm) for filters or polarizers on the outside for a waterproof solution (even underwater). For thread sizes above 77mm we sell an extension for a 95mm external thread so you can use 95mm polarizers or filters. They are both available in Shop By Parts.
3. You can purchase a Outex Dome port (both/either size would work), then use an Outex Dome clamp to fit/match the lens' diameter size. In other words, since the lens filter thread is taken/ocupied by the polarizer or ND filter, you'd clamp the Outex clamp on the perimeter of your lens. Both/either Dome Kits include a clamp (or adaptor). See example image below using an ND filter inside of a Dome.
4. Or you can use them inside the housing if you're looking for waterproofed protection, but with limited access if it's a variable filter.
You can shop for External Thread Front Ports in Shop By Parts
If you still have questions or need help contact our tech support team at firstname.lastname@example.org or (818) 583-7731.