Applicable models: the Nikon D4, D3x, D3S, D3 and D700, d800, d800e, D2XS, d2x, D2H, F6, the DK-19 is rubber eye cup, installed between the camera's viewfinder and camera built-in eyepiece DK-17; The benefit of installing DK-19 is it can block stray light for easy, comfortable and clear viewing. Installation method is very simple, Screw down the original DK-17 circular eyepiece of cameras, then install the DK-19 on the camera's viewfinder