Applicable models: Nikon F6, d2x, D3x, D3 and D700, d800, d800e, D810, D4s, D4 mounted on the outside of the eyepiece can block stray light for comfortable, convenient and clear viewing. Corresponding to the DK-17 (F6, D2X standard configuration), DK-17A, DK-17C; Anti off lock function