The first post and thorough description of the double-ring system that I saw was from dchinell. Thanks, Bear, for providing this background. After switching to a mod of his system, my setup got so easy that I never switched back to the Hennessey knot. As mentioned earlier (see and related photos, both the webbing and rings were from REI. I had a long chat with one of the REI staff in the climbing department before choosing--I felt that if climbers were using these items, on which their lives depend, the strength of materials would be more than enough for hammock use.