Helpful tip to save lives. A guy that I worked with at Cadman was also a consultant for the ski companies. He was called into court when ever they were being sued after a death. The most common cause of death was the use of metal d-rings and quick snaps. If you use a d-ring at either end of the rope to attach the rope to the boat or the tube to rope you can get some one killed. I was using a aluminum dring at the time on my tube. When the line is stressed pass its breaking strength then the dring can became a missile and kill some one. Getting hit by a 6 0z's of metal doing well over a hundred is not good. A hit to the head or upper body could and has killed. All tubs have a warning not to use a dring right on the tube where you would hook it up. He said it was very sad to tell parents that little jimmy was dead because they did not read the warning right in front of them. I have seen countless numbers of tubes hooked up in this way. Please tie the line or use a built in loop.