This Ikelite 6441.31 External Color Correction Filter has a diameter of 2.2". The filter is shortened in-order to avoid vignetting on certain housings when the camera lens is at the widest angle.
This filter alters the blue color of warm salt water to give your subject a rich, natural tone. The filter also enhances the contrast of underwater photographs. It should only be used with available light.
6441.31 External Color Filter for 2.2" Ports for Bluewater (Shortened)