Seattle, WA. Calvin Tang recently introduced me to this special tool. At first I had no clue what to do with it when he handed it to me 70 feet below Cove 2. It took about 10 seconds to figure it out then I spent the remainder of the dive wondering how I ever got along without one! As a matter of fact I didn't want to give it back when he asked for it. I have since then incorporated one into my dive kit and it's revolutionized the way I do things underwater. Send Calvin a message if you want one. Hit the link below to his site.