The Nikon DK-19 minimises the amount of stray light that enters the viewfinder & enables more comfortable viewing. It is particularly helpful for photographers who wear glasses. The Nikon DK-19 minimises the amount of stray light that enters the viewfinder & enables more comfortable viewing. It is particularly helpful for photographers who wear glasses. The Nikon DK-19 eyecup is compatible with the Nikon D2 series, D3 series, Df, D4, D700, D800/E, D800E, D810 & F6.