Not 100% on how to correctly use this. Could some one upload a pic of it on their computer?
My gear is put away but it's simple, I use this to secure my gauge console: The hook clips to a metal loop on my BCD and the long elastic cord secures to my console, when I want to view my gauges I simply reach for them and stretch the cord to have a look, when finished it springs back to where it was...
I have other types but like this one the best...
You loop the rope end to a lanyard hose on your console. Did not like it so I returned it for a similar item with caribeeners on each end.
I was a little baffled by it too. I finally decided the only way it could work would be to push the little closed loop end (at one end of the long tube like retainer) through a D-ring on my BCD. Then I threaded the larger clip end through the closed loop end after making the opening larger by pulling it out a ways through the tube. Then just pull it tight and you will have the elastic pull looped through itself around the D-ring to hold it fast, with the protective tube extending away toward the clip end. I guess the tube is to protect the elastic and to keep it closely gathered. I used this device for a few years on my console w/air gauge and computer and compass. When it finally broke, I just retied the elastic and continued using it--although the tube fell off and was lost when the elastic snapped. I continued to use it until I got a little better one that came as a pkg deal with a new dive light. I still have it and another one just like it. Very simple and easy to use--Just grab and pull whatever it is connected to and bring it into range and then let it go when you're done.
Due to its length, I hook the plastic clip (1pm position in the product picture) to the metal (or plastic) O on my BC at the chest level (I prefer the permanent/ nonmoveable one. the moveable one is the one at the end of the BC shoulder strap adjuster and ends up in different positions depending on how my tank is positioned, wet suit use, and general comfort that day. Using the non-movable one, I always have it in a consistent location.
Leave the rubber sleeve on the elastic. Put your computer (which I assume is mounted into a housing with your pressure gauge through the loop (2pm position in the picture).
You can then tighten down the sleeve to minimize the loop to a reasonable size where the elastic hooks to the clip (7pm on the picture).