Has only one layer of glass but is multiply coated 

Also 67mm. The filter is screwed into a 67mm thread and there is a 67mm thread available on the filter side to attach additional filters. (Pol./ND) 

The filter has the same thread pitch as any other standard photo filter. 

The filter must have a thread diameter of 52mm on the FZ300. The filter must therefore be ordered in size 52mm! 

think you should ask the manufacturer about that. 

The UV filter is good for protecting the front lens from contamination and the inner workings of your lens from UV radiation. Good filters swallow almost no light and have no color cast. In most cases, however, the UV protection of the lenses in the lens is not necessary, since they are already coated and have their own protection. The filters do a good job of protecting against dirt and scratches. 

Dear Sir or Madam, As long as the lens size is right, it will fit your lens!