The intended use of a rubber eyecup is to make the use of a viewfinder more comfortable. The rubber acts as a cushion between a photographer's eye and the viewfinder.

The intended use of a rubber eyecup is to make the use of a viewfinder more comfortable. The rubber acts as a cushion between a photographer's eye and the viewfinder.

A soft rubber eyecup prevents a photographer from scratching their expensive glasses or sunglasses. It also prevents stray light from entering the camera's viewfinder.

This rubber attaches to Nikon's pro line camera eyecups. The rubber comes with an attachment which secures the rubber against the camera eyecup.