FODSLR 5pcs Dk-21 Eye Cup Eyecup for Nikon D7000 D300 D300s D90 D80 D200 Dk-23 Prevents light from entering the viewfinder; useful when shooting long exposure photos since it Protects the viewfinder from dust, dirt and moisture. It is especially useful to eyeglass wearers. Block out unwanted light from your viewfinder.