The Hydrophobia Eyepiece EP-C for Most Canon DSLR Cameras (Black) from Think Tank is required for use on your Hydrophobia rain cover. It allows you to see through the camera's eyepiece once the rain cover is installed. It should be noted that this eyepiece does not fit the Canon Mark III, Mark IV models and the EOS 7D.
EOS 1Ds Mk. II, 1D Mk. II, 5D Mk II, 5D, 50D, 60D, Digital Rebel Series
Sony A900, A700
Hydrophobia 300-600 V2.0, 70-200, Flash 70-200