For the Canon EOS 5D MKII digital SLR camera, the Eg-S Focusing Screen (Manual Precision Matte) is designed for manual focusing with high-speed lenses (f/2.
8 or faster).
The Ee-S screen has finer microlenses than the Ee-A or Eg-D along with a steeper parabola of focus to make the image pop in and out of focus more vividly in the viewfinder.
However, the Eg-S focusing screen is not recommended for slower lenses because it's not very bright.