The front lens of the lens is strongly curved and has a permanently integrated lens hood, threads for screwing are not available on the optics. The cap is placed over the lens hood and held in place by latches. I don't see any options for attaching a filter, and I'm not aware of any factory solutions or products from other manufacturers. 

Hello, when focusing, the front lens moves back and forth, but it doesn't rotate. The use of a polarizing filter is therefore unproblematic. 

No other radio system. 

No other radio system. 

All gradient filters, whether made of glass or plastic, are coated filters. As far as I know, there are no gradients in the glass. Is due to the production of glass. Nevertheless, there are good to very good results with the glass filters. Lee filters are usually made of plastic, with the ordinal number CR39, from which glasses are also made. They are also coated. In fact, they are very good. Due to this complex production, the filters cost a lot of money. And at Lee Filters they are not cheap especially, although they are made out of "plastic", except for the IR filters. They're made of glass.