Boat Buzz

I found three of these on the boat, uninstalled, and have no idea what they would be for. Any ideas?
https://picasaweb.google.com/1136153585 ... 2250409346

Got Me.

The way they latch you would think they were for fuel or something, but I have never seen anything like them. Send the picture with the numbers to Staib, he may know something.