The DK-17A ;Anti-Fog Eyepiece from Nikon ;is
a replacement viewfinder eyepiece that uses specially ;surface-coated
transparent plastic to reduce condensation or fogging. Designed for use
in humid or cold weather, when fogging is most likely to occur. The
DK-17A is compatible with Nikon D2 series, D3 series, D4, D700, D800,
D800E ;and F6 cameras.