I think it's a great idea, couldn't tell you how many times I've gotten my flip line hung up on something. We have something similar for our lanyards in line work but it's bulky and heavy. The one I had is made by Buckingham and works on the seat belt principle but I never liked it or trusted it. Since this device does not hold your weight, but just retracts the slack in the flip line, I could see a niche for it if it's not too heavy. Go for it! That's what America is all about. The best of luck to you.