underwater gray card

I'd like to buy a gray card for underwater use - but haven't been able to track one down on the internet - can anyone suggest a supplier?

Thanks

Ivor

The ones from www.rmimaging.com look like they might work.

At least they seem to be made out of a plastic material instead of the usual cardboard.

My plastic grey card is from Calumet.

www.calumetphoto.com

Dark room people are the "other lot" who need water proof grey cards!

Alex

My plastic grey card is from Calumet.

 

www.calumetphoto.com

 

Dark room people are the "other lot" who need water proof grey cards!

 

Alex

Alex,

which grey card is it you use?... there are two listed on this site. One is a "Photographers Grey Card" the other is a "Kodak Grey Card 18%". I'm guessing it's the latter?

Thanks.