Sometimes, you swear what you composed was razor focused, only to find that its not in Aperture 2 or Nikon ViewNX. Blame it on the small viewfinder or get a new pair of specs after an eye check. Or forget about using the default viewfinder piece - Nikon DK-23 rubber eye cup, while replacing it with the Nikon DK-21M.
It promises a magnification of your viewfinder by over 17%, giving you greater confidence of knowing what you are aiming is what the camera is aiming.
Note to adjust your diopter dial to make effective use of the upgrade. Retails for $24.95.