Nikon NIKKOR Z 800mm f/6.3 VR S Lens - Manual (Page 34)

Press the points on either side of the slip-in filter
holder and open the cover.
Insert a 46 mm screw-on filter.
Depending on their shape, some filters cannot be used with the slip-in filter
holder. Use filters that fit the holder.
Filters
34
2.
3.