The Think Tank EP-CMIII eyepiece is required to use any Hydrophobia rain cover with the Canon EOS 1D Mark IV, 1D Mark III, and 1Ds Mark III DSLR cameras. The EP-CMIII can also be used with Olympus E3 and E30 cameras.

Compatible with the Hydrophobia 300-600 V2.0, Hydrophobia 70-200 and Hydrophobia Flash 70-200.

Compatible Hydrophobia Rain Covers:
Hydrophobia 300-600 V2.0
Hydrophobia 70-200
Hydrophobia Flash 70-200

Compatible DSLR Cameras:
EOS 1D Mark IV
EOS 1Ds Mark III
EOS 1D Mark III
Olympus E3
Olympus E30