Aquatica port extension for 17-40L?

Solved: I need port #18457 Someone please delete this post.

I'm hoping that someone here can tell me which extension I need for a Canon 17-40L.

Hah ! came in too late, glad you got the info anyway. don't bother about deletion, the info might be usefull for somebody else, We still (mostly me) haven't had the time to run trough all the Canon lenses and try them out u/w, I off to a shoot with Todd Essick for a week and as soon as i'm back i'll book some much needed time at our test facility pool.