The phot r dk 21 rubber eye cup for nikon cameras attaches to the viewfinder eyepiece of the nikon d80 d90 d200 d600 d610 d750 d7000 digital cameras it is an integral part of the camera which is installed in the camera viewfinder eyelid contact it protects the eyes from hitting the viewfinder it also minimises extraneous light and reducing vision fatigue the eyepiece is designed for comfort so you can easily hold the camera to your eye while you frame the shot helping to compose pho