It looks to me that ya'll use d-rings a lot like what's on a motorcycle helmet. pull the strap through both rings, then back around through only one ring. Am I correct?

So if I am correct and us hammock-ers use these for quick adjustments of sag, where do I get D-rings rated for this kind of stress?

I just got a Clark NX-200. I love it, but I am not real good with knots. I can tie them, just not always exactly where I want them.