red filter on ikelite casing

i got my ikelite casing for my cp950 second hand and it did not come with instructions. can anyone please explain the use of the red filter that it comes with?

The red filter is for taking natural light shots without a strobe or supplemental lighting.

Cheers

James

ahh i feel dumb now. then again, thanks to the wonders of photoshop, i easily colorcorrected all my shots. thanks for the info!