At last, the Z system has got its own, native teleconverters. Nikon indicates they had the 70-200/2.8 S as the first targeted lens for use with these TCs. However, the already launched 120-300/.8 Nikkor S should be a hot candidate for these new converters as well. They have a proment, protruding neck and hence will not fit most of the existing Z lenses, but I see the design as an indication future long lenses will be fully compatible with them.
The design involves aspherical element(s), fluorine coating and some strongly curved elements.Nikon assured me virtually noi loss of image quality eas to be expected with the 70-200 and the 1.4X, perhaps slightly less perfect with the 2X.
The build is very robust and weather sealing is claimed to be to the highest standard.