The Nikon Type E Focusing Screen is an interchangeable focusing screen compatible with the Nikon F3 series cameras. This Matte/Fresnel screen features a 3mm circular clear rangefinder spot and a 12mm reference circle, with etched horizontal and vertical grid lines. For architectural and other precision photography. The 12mm outer circle corresponds with the exact 80/20 heavy center-weighted metering area used specifically on the Nikon F3 series.