The Canon Eb eyecup is supplied with many of their SLR cameras as standard equipment, providing effective cushioning and shielding of stray light.
Compatiblity:
EG is for:
Canon EOS 1DS mark 3, 1DS mark IV, 7D, 5DIII
DK-23 is for:
Nikon D300, D300S, D70, D7100